Description
ORGANIC ELECTRONIC DEVICE
Technical Field
[1] The present invention relates io electronic devices having an n-lype organic
compound layer in an electrode for hole injection or hole extraction. More particularly, the present invention relates to electronic devices capable of lowering the energy barriers for hole injection or hole extraction.
Background Art
12] Electronic devices such as solar batteries, organic luminescence devices, or organic
transistors include two electrodes and an organic compound disposed between the electrodes. Solar batteries, for example, generate electricity by using the electrons and holes separated from exciton generated in organic compound layers in response to solar energy. Organic luminescence devices inject electrons and holes into the organic compound layer from two electrodes to convert electric currents into visible light. Organic transistors transport the holes or electrons generated in organic compound layers between a source electrode and a drain electrode in response to the voltage applied to a gate. Electronic devices may further include an electron/hole injection layer, an electron/hole extraction layer, or an electron/hole transporting layer in order to improve performance.
|3] The interface between electrodes having a metal, a metal oxide, or a conductive
polymer, and an organic compound layer, however, is unstable. An externai heat, an internally generated heat, or the electric field applied to the electronic devices could adversely affect the performance of electronic devices. A driving voltage of electronic devices could be increased by the conductive energy difference between an electron/ hole injection layer or an electron/hole transporljng layer and an organic compound layer. Therefore, it is important to stabilize the interface between the electron/hole injection layer or the electron/hole transporting layer and the organic compound layer, as well as minimizing the energy barrier for injecting/extracting electron/hole into/ from electrodes. Disclosure of Invention
Technical Problem
[41 Electronic devices have been developed to control the energy difference between
electrodes and an organic compound layer disposed between the electrodes. In a case of organic luminescence devices, an anode electrode is controlled to have a Fermi energy similar to the Highest Occupied Molecular Orbital (HOMO) energy of a hole injection layer, or a compound having the HOMO energy similar to the Fermi energy
ol the anode electrode is selected for the hole injection layer. Because the hole
injection layer should be selected in view of the HOMO energy of the hole transporting
layer or light emitting layer, in addition to the Fermi energy of the anode electrode,
there is limitation in choosing compounds for the hole injection layer.
15] Therefore, a melhod for controlling the Fermi energy of an anode electrode has
been generally adopted in manufacturing organic luminescence devices. Compounds for anode electrode, however, are limiled. Organic (ransistors, for example, have used gold or novei metals for a source/drain electrode. Such gold or novei metals, however, arc cxpcnsive and hard Io process using industrial melhods, thus reslricting their ap-plicalion and structure in organic transistors.
Technical Solution
16] According to an aspect of the present invention, an electronic device comprises: a
firsl clcclrode to inject or extract hole, the first electrode including a conductive layer and an n-lype organic compound layer disposed on the conductive layer; a second electrode (o inject or extract electron; and a p-type organic compound layer disposed hclwccn the conductive layer of the first electrode and the second electrode, the p-type organic compound layer forming an NP junction between the n-type organic compound layer of the first electrode and the p-type organic compound layer, wherein an energy difference between a lowesl unoccupied molecular orbital (LUMO) energy of Ihe n-typc organic compound layer of the first electrode and a Fermi energy of the conductive layer of the first electrode is about 2eV or less; and wherein an energy difference between the LUMO energy of the n-type organic compound layer of the first clcclrode and a highest unoccupied molecular orbital (HOMO) energy of (he p-(ypc organic compound layer is about leV or less.
[7J According (o another aspect of the present invention, an organic luminescence
dcvicc comprises an anode including a conductive layer and an n-type organic
compound laycr disposed on the conductive layer; a cathode; and a p-type organic
compound laycr disposed between the conductive layer of the anode and the cathode,
the p-typc organic compound layer fonning an NP junction between the n-type organic
compound laycr of the anode and the p-type organic compound layer, wherein an
energy difference between a LUMO energy of the n-type organic compound layer of
the anodc aiul a Fermi energy of the conductive layer of the anode is about 2eV or less;
and wherein an energy difference between the LUMO energy of the n-type organic
compound laycr of the anode and a HOMO energy of the p-type organic compound
laycr is ahoul IcV or less.
[8] According io another aspect of the present invention, an organic solar batlery
comprises: an anode including a conductive layer and an n-type organic compound laycr disposed on the conductive layer; a cathode; and an electron donor layer disposed
between the conductive layer of the anode and the cathode, the electron donor layer
including a p-type organic compound layer and forming an NP junction between the n-
typc organic compound layer of the anode and the p-type organic compound layer,
wherein an energy difference between a LUMO energy of the n-(ype organic
compound layer of the anode and a Fermi energy of the conductive layer of the anode
is about 2eV or less; and wherein an energy difference between the LUMO energy of
me n-(ype organic compound layer of the anode and a HOMO energy of the p-type
organic compound layer is about leV or less.
19] According (o further aspect of Ihc present invention, an organic transistor
comprising: a source electrode; a drain electrode; a gate; an insulating layer disposed on the gate; a p-type organic compound layer disposed on the insulating layer; and an n-lype organic compound layer disposed between the source electrode or the drain electrode and the p-type organic compound layer, an NP junction being formed between the n-type organic compound layer and the p-type organic compound layer, wherein an energy difference between a LUMO energy of the n-type organic compound layer and a Fermi energy of the source electrode or the drain electrode is about 2eVor less; and wherein an energy difference between the LUMO energy of the n-type organic compound layer and a HOMO energy of the p-type organic compound layer is about leV or less.
Advantageous Effecte
110] Electronic devices according Io exemplary embodiments of the present invention
include an n-type organic compound layer in addition to a conductive layer as an electrode for hole injection or hole extraction. The n-type organic compound layer is chosen so that the energy difference between the LUMO energy of the n-type organic compound layer and the Fermi energy of the conductive layer which contacts one side of the n-type organic compound layer is about 2eV or less and the energy difference between the LUMO energy of the n-type organic compound layer and the HOMO energy of the p-type organic compound layer which contacts the other side of the n-type organic compound layer is about le V or less. Because the n-type organic compound layer lowers the energy barriers for hole injection or hole extraction and forms an NP junclion between the n-type organic compound layer and the p-type organic compound layer, the electronic devices can use various materials as electrodes, thereby simplifying a process and improving efficiency.
Description of Drawings
f 11 ] A more complete appreciation of the invention, and many of the attendant
advantages thereof, will be readily apparent as the same becomes better understood by refcrence to the following detailed description when considered in conjunction with the
accompanying drawings, wherein:
[12] Fig. l (a) and (b) respecţively show the energy levels of a firsl electrode for hole
injection or hole extraction in an electronic device according to an exemplary embodiment of the presenl invention, before and after employing an n-type organic compound layer into the first electrode;
113] Fig, 2 shows a NP junction formed between an n-type organic compound layer of a
firsl electrode for hole injection or hole extraction and a p-type organic compound
layer in an electronic device according to an exemplary embodiment of the present
invention;
114] Fig. 3 is a schematic secţionai view showing an organic luminescence device
according to an exemplary embodiment of the present invention;
1151 Fig. 4 shows an ideal energy level of an organic luminescence device;
116] Fig. 5 shows an energy level of an organic luminescence device according to an
exemplary embodiment of the present invention;
[ 17] Fig. 6 is a schematic secţionai view showing an organic solar battery according to
an exemplary embodiment of the present in veni ion;
[ 18] Fig. 7 is a schematic secţionai view showing an organic transislor according to an
exemplary embodiment of the present invention;
i 19] Figs 8 and 9 are schematic section views each showing a stacked organic lu-
minescence device, according to an exemplary embodiment of the present invention,
respecţi vely;
[20] Fig. 10 is a graph showing UPS data of a gold film and a HAT film disposed on the
gold film;
[21 ] Fig. 11 is a graph showing the current-voltage characteristics of Rxample 2 and
Comparative Example 1;
122] Fig. 12 is a graph showing the current-voltage characteristics of Example 3 and
Comparative Example 2;
[23] Fig. 13 is a graph showing the current-voltage characteristics of Examples 4 to 7;
and
[24] Fig. 14 is a graph showing the current-voltage characteristics of Example 8 and
Comparative Examples 3-4.
Mode for Invention
[25] In the following detailed description, only the preferred embodiment of the
invention has been shown and described, simply by way of illustration of the best mode contcmplated by the inventors of carrying out the invention. As will be realized, the invention is capable of modification in various obvious respecls, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not restrictive.
t26] The electronic device according to an exemplary embodiment of the present
invention includes a first electrode to inject or extract holes, a second electrode to
inject or extract electrons, and an organic compound layer having p-type semi­
conductor properly (hereinafter 'p-type organic compound layer') disposed between the
first and second electrodes. The p-type organic compound includes a hole injection
layer, a hole transporting layer, or an emitting layer. The electronic device may further
include at least one organic compound disposed between the p-type organic compound
layer and the second electrode.
[27] The first electrode includes a conductive layer and an organic compound layer
having an n-type semiconductor property (hereinafter 'n-type organic compound layer') disposed on the conductive layer. The conductive layer includes metal, metal oxide, or a conductive polymer. The conductive polymer may include an electrically conductive polymer. The n-type organic compound layer has a predetermined LUMO energy, with respect to the Fermi energy of the conductive layer and the HOMO energy of the p-type organic compound layer.
128 j The n-type organic compound layer of the first electrode is chosen to decrease the
energy difference between the LUMO energy of the n-type organic compound layer of the first electrode and the Fermi energy of the conductive layer of the first electrode and the energy difference between the LUMO energy of the n-type organic compound layer and the HOMO energy of the p-type organic compound layer. Therefore, holes are easily injected into the HOMO energy of the p-type organic compound layer through the LUMO energy of the n-type organic compound layer of the first electrode. Alternatively, holes are easily extracted through the LUMO energy of the n-type organic compound layer of the first electrode from the HOMO energy of the p-type organic compound layer.
[29] The energy difference between the LUMO energy of the n-type organic compound
layer of the first electrode and the Fermi energy of the conductive layer of the first
electrode, for example, is about 2 eV or less(0 eV is not included), specifically about
leV or less(0 eV is not included). The energy difference may preferably be O .01~2eV
in view of material selection. The energy difference between the LUMO energy of the
n-type organic compound of the first electrode and the HOMO energy of the p-type
organic compound layer is about l e V or less(0 eV is not included), specifically about
0.5eV or less(0 eV is not included). The energy difference may preferably be O
.01~leV in view of material seleclion.
[30] When the energy difference between the LUMO energy of the n-type organic
compound layer of the first electrode and the Fermi energy of the conductive layer of the first electrode is greater than about 2eV, the effect of surface dipole or gap state on the energy barrier for hole injection or hole extraction is diminished. When the energy
difference between the LUMO energy of the n-type organic compound layer and the
HOMO energy of the p-type organic compound layer is greater than about l e V, the NP
junclion between the p-type organic compound layer and the n-type organic compound
layer of the firsl eleclrode is not easily generated, thereby raising a driving vollage for
hole injection or hole extraction. The range of the LUMO energy of the n-type organic
compound layer is not limited to the above stated range, but is greater than about OeV
energy difference, wilh respect to the Fermi energy of (he conductive layer of the first
eleclrode and the HOMO energy of the p-type organic compound layer.
1.31J Fig. l (a) and (b) respectively show the energy levels of the first electrode for hole
injection or hole extraction according to an exemplary embodiment of the present invention, before and after employing the n-type organic compound layer in the first electrode. The conductive layer has a higher Fermi energy (E ) than the Fermi energy (E ) of the n-type organic compound layer (a). Vacuum Level (VL) indicates the energy level at which electron freely moves in the conductive layer and the n-type organic compound layer.
[32] When the electronic device employs the n-type organic compound layer as a portion
of the first electrode, the conductive layer makes contact with the n-type organic
compound layer. The electron moves from the conductive layer to the n-type organic
compound layer so that the Fermi energies (E ) of the two layers are the same (b). As
a result, surface dipole is formed on the interface between the conductive layer and the
n-type organic compound layer, and the VL level, the Fermi energy, HOMO energy,
and LUMO energy of the first electrode is changed as shown in Fig. l (b).
[33] Therefore, although the energy difference between the Fermi energy of the
conductive layer and the LUMO energy of the n-type organic compound layer is big,
the energy barrier for hole injection or hole extraction can be reduced by contacting the
conductive layer and the n-type organic compound layer. Further, when the conductive
layer has a Fermi energy greater than a LUMO energy of the n-type organic compound
layer, the electrons move from the conductive layer to the n-type organic compound
layer, thereby forming gap state at the interface of the conductive layer and the n-type
organic compound layer. Thus, the energy barrier for transporting electrons is
minimized.
[34] The n-type organic compound layer includes, but not limited to,
2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) having LUMO
energy of about 5.24eV, fluoro-substituted 3,4,9,10-Perylenetetracarboxylic di-
anhydride (PTCDA), cyano-substituted PTCDA, naphthalene-tetra-
caboxylic-dianhydride (NTCDA), fluoro-substituted NTCDA, or cyano-substituted
NTCDA.
[35] The electronic device according to an exemplary embodiment of the presenl
invenlion includes a p-type organic compound layer contacting the n-type organic compound layer of the first electrode for hole injection or hole extraction. Therefore, an NP junction is formed in the electronic device. Fig. 2 shows the NP junction formed belween the n-lype organic compound layer of the first electrode and the p-type organic compound layer.
136] The energy difference between the LUMO energy of the n-type organic compound
layer of the first electrode and the HOMO energy of the p-type organic compound
layer is reduced when the NP junction is generated. Therefore, eleclrons or holes are
easily generated in response to an externai voltage or light. The holes in the p-type
organic compound layer or the electrons in the n-type organic compound layer of the
first electrode are also easily generated due to the NP junction. Because the electrons
and holes are generated together at the NP junction, the electrons are transported to the
conduclive layer of the first electrode (hrough the n-type organic compound layer of
the firsl electrode and the holes are transported to the p-type organic compound layer.
(37] In order that the NP junction effectively transports the holes to the p-type organic
compound layer, the difference between the LUMO energy of the n-type organic compound layer of the first electrode and the HOMO energy of the p-type organic compound layer has a predelermined level. The difference between the LUMO energy of the n type organic compound layer of the first electrode and the HOMO energy of the p-type organic compound layer, for example, is about leV or less, specifically about 0.5eV or less.
138] The electronic device according to exemplary embodiments of the present invention
includes, but not limited to, an organic luminescence device, an organic solar battery,
or an organic transistor.
[39] Organic Luminescence Device
140] Organic luminescence devices include an anode, a cathode, and a p-type organic
compound layer disposed between the anode and the cathode. The p-type organic
compound layer includes a hole injection layer, a hole transporting layer, or an
emilting layer. Organic luminescence devices may further include at least one organic
compound layer disposed between the p-type organic compound layer and the cathode.
When the organic luminescence device includes a plurality of the organic compound
layers, the organic compound layers may be formed of the same material or different
materials. Fig. 3 shows an organic luminescence device according Io an exemplary
embodimenl of the present invention.
|411 Referring Io Fig. 3, an organic luminescence device includes a substrate 31, an
anode 32 disposed on the substrate 31, a p-type hole injection layer (HIL) 33 disposed on the anode 32 and to receive holes from the anode 32, a hole transporting layer (HTL) 34 disposed on the hole injection layer 33 and to transport the holes to an
emitting Jayer (EML) 35, the emitting layer 35 disposed on the hole transporting layer 34 and to emit light by using the electrons and holes, and an electron transporting layer (ETL) 36 disposed on the emitting layer 35 and to transport the electrons from a cathode 37 to the emitting layer 35, and the cathode 37 disposed on the electron transporting layer 36. The hole transporting layer 34, the emitting layer 35, or the electron transporting layer 36 may be formed of the same organic compound or different organic compounds.
[42] According to another exemplary embodiment of the present invention, an organic
luminescence device may include a substrate 31, an anode 32 disposed on the substrate 31, a p-(ype hole transporting layer 34 disposed on the anode 32, an emitting layer 35 disposed on the hole transporting layer 34, an electron transporting layer 36 disposed on the emitting layer 35, and a cathode 37 disposed on the electron transporting layer 36. The emitting layer 35 or the electron transporting layer 36 may be formed of the same organic compound or different organic compounds.
[43] According to further exemplary embodiment of the present invention, an organic lu-
minescence device may include a substrate 31, an anode 32 disposed on the substrate 31, a p-type emitting layer 35 disposed on the anode 32, an electron transporting layer 36 disposed on the emitting layer 35, and a cathode 37 disposed on the electron transporting layer 36. The electron transporting layer 36 may be formed of organic compound.
[44] Still referring to Fig. 3, the anode 32 transports holes to the hole injection layer 33,
the hole transporting layer 34, or the emitting layer 35, and includes a conductive layer
32a and an n-type organic compound layer 32b. The conductive layer 32a is formed of
metal, metal oxide, or a conductive polymer. The energy difference between the
LUMO energy of the n-type organic compound layer 32b and the Fermi energy of the
conductive layer 32a is about 2eV or less, specifically, about leV or less. The energy
difference between the LUMO energy of the n-type organic compound layer 32b and
the HOMO energy of the p-type hole injection layer 33 is about less le V or less,
specifically about 0.5eV or less. An NP junction is formed between the n-type organic
compound layer 32b of the anode 32 and the p-type hole injection layer 33.
[45] When the hole transporting layer 34 or the emitting layer 35 is formed of the p-type
organic compound according to another exemplary embodiment of the present
invenfion, the energy difference between the LUMO energy of the n-type organic
compound layer 32b and the HOMO energy of the p-type hole transporting layer 34, or
the p-type emilting layer 35 is about leV or less, specifically 0.5eV or less. The NP
junction is formed between the n-type organic compound layer 32a of the anode 32 and
the p-type hole transporting layer 34, or the p-type emitting layer 35.
[46] When the energy difference between the LUMO energy of the n-type organic
compound layer 32b and the Fermi energy of the conductive layer 32a is greater than about 2eV, the effect of surface dipole or gap state on the energy barrier for hole injection to the p-type injection layer 33 is diminished. When the energy difference between the LUMO energy of the n-type organic compound layer 32b and the HOMO energy of the p-type hole injection layer 33 is greater than about l e V, holes or electrons are not easily generated in the p-type hole injection layer 33 or the n-type organic compound layer 32b, respectively. Therefore, a driving voltage for the hole injeclion is raised.
[47] Fig. 4 shows an ideal energy level of an organic luminescence device. With this
energy level, the energy loss for injecting the holes and electrons from the anode and
the cathode, respectively, is minimized. Fig. 5 shows an energy level of an organic lu­
minescence device according to an exernplary embodiment of the present invention.
[48] Referring Fig. 5, an organic luminescence device according to another exemplary
embodiment of the present invention includes an anode having a conductive layer and an n-type organic compound layer (shown in Fig. 3), a p-type hole injection layer (HIL), a hole transporting layer (HTL), an emitting layer (EML), an electron transporting layer (ETL), and a cathode. The energy difference between the LUMO energy of the n-type organic compound layer of an anode and the Fermi energy of the conductive layer of the anode is about 2eV or less and the energy difference between the LUMO energy of the n-type organic compound layer of the anode and the HOMO energy of the p-type hole injection layer is about leV or less. Because the energy barriers for hole/electron injection or extraction are lowered by the n-type organic compound layer of the anode, the holes are easily transported from the anode to the emitting layer by using the LUMO energy of the n-type organic compound layer of the anode and the HOMO energy of the p-type hole injection layer.
[49] Because the n-type organic compound layer of the anode lowers the energy barrier
for injecting holes from the anode to the p-type hole injection layer, the p-type hole
transporting layer or p-type emitting layer, the conductive layer of the anode can be
formed of various conductive materials. The conductive layer, for example, can be
formed of the same materials to the cathode. When the anode is formed of the same
material to the cathode, such as, the conductive material having low work function, a
stacked organic luminescence device can be manufactured.
[50] Figs. 8 and 9 show stacked organic luminescence devices according to an
exemplary embodiment of the present invention, respectively. Referring to Fig. 8, an
anode 71 of an organic luminescence device is connected to a cathode 75 of adjacent
organic luminescence device in serial. The anode 71 includes a conductive layer and an
n-type organic compound layer.
[51} Referring to Fig. 9, an organic luminescence device forms an equivalent structure in
which a plurality of reating units, each having an organic compound layer 83 and an intermediate conductive layer 85, is disposed between an anode 81 and a cathode 87. The intermediate conductive layer 85 includes a conductive layer and an n-type organic compound layer. The conductive layer is formed of a transparent material having a similar work function to that of the cathode 87 and a visible light transmission rate of about 50% or more. When a non-transparent material forms the conductive layer, the thickness of the conductive layer is thin enough to be transparent. The non-transparent material, for example, includes aluminum, silver, or copper. When Al forms the conductive layer of the intermediate conductive layer 85, the conductive layer, for example, has a Ihickness of about 5 to 10 nm. Because a brightness is increased in proportion to the number of the staked organic luminescence devices operated in response to the same driving voltage, the stacked organic luminescence device has an improved brightness.
[52] Hereinafter, each layer of the organic luminescence device according to an
exemplary embodiment of the present invention is illustrated. Each layer can be
formed of a single compound or a combination of two or more compounds.
[53] Anode
[54] An anode injects holes into a p-type organic compound layer such as a hole
injection layer, a hole transporting layer, or an emitting layer. The anode includes a conduci ve layer and an n-type organic compound layer. The conductive layer includes metal, metal oxide or a conductrve polymer. The conductive polymer may include an electrically conductive polymer.
[55] Because the n-type organic compound layer lowers the energy barrier for injecting
holes to the p-type organic compound laycr, the conductive layer can be formed of
various conductive materials. The conductive layer, for example, has a Fermi energy of
about 3.5 to 5.5eV. As exemplary conductive material, there are carbon, aluminum,
vanadium, chromium, copper, zinc, silver, gold, or alloy of the forgoing materials; zinc
oxide, indium oxide, ţin oxide, indium ţin oxide (ITO), indium zinc oxide, and similar
metal oxide; or a combination of oxide and metal, such as ZnO:Al or SnO :Sb. A top
emission type organic luminescence device may use both a transparent material and a
non-transparent material having high light reflectance as the conductive layer. A
bottom emission type organic luminescence device uses a transparent material or a
non-transparent material having a thin thickness as the conductive layer.
[56] The n-type organic compound layer is disposed between the conductive layer and
the p-type organic compound layer, and injects holes into the p-type organic compound layer under a low electric field. The n-type organic compound is selected so that the energy difference between the LUMO energy of the n-type organic compound layer of the anode and the Fermi energy of the conductive layer of the anode is about 2eV or
less, and the energy difference between the LUMO energy of the n-type organic compound layer of the anode and the HOMO energy of the p-type organic compound layer is about leV or less.
f 57] The n-type organic compound layer, for example, has the LUMO energy of about 4
to 7 eV and the electron mobility of about 10 cm2/Vs to about Icm2/Vs, specifically about 10~6cm2/Vs to about 10"2cm2/Vs. When the electron mobility is less than about 10
-R -5
cmVVs, i( is not easy to inject holes from the n-type organic compound layer into the p-type organic compound layer. When the electron mobility is greater than about l cm2 / Vs, such an organic compound is crystalline rather than amorphous. Such a crystalline organic compound is not easily used for organic EL device.
[58] The n-type organic compound layer is formed by a vacuum deposition or solution
process. The n-type organic compound layer includes, but not limited to,
2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane(F4TCNQ), fluoro-substituted
3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), cyano-substituted PTCDA,
naphthalene-tetracaboxylic-dianhydride (NTCDA), fluoro-substituted NTCDA, cyano-
substituted NTCDA, or hexanitrile hexaazatriphenylene (HAT).
[59] Hole Injection laver (HIL) or Hole Transporting Layer (HTL)
[60] Either the hole injection layer or the hole transporting layer can be formed of a p-j
type organic compound layer disposed between the anode and the cathode. Because the p-type hole injection layer or the p-type hole transporting layer and the n-type organic compound layer of the anode form an NP junction, the holes formed at the NP junction are transported to the emitting layer through the p-type hole injection layer or the p-type hole transporting layer.
[61] The HOMO energy of the p-type hole injection layer or the p-type hole transporting
layer has, for example, about leV or less energy difference or about 0.5eV or less
energy difference, with respect to the LUMO energy of the n-type organic compound
layer. The p-type hole injection layer or the p-type hole transporting layer includes, but
not limited to, an arylamine compound, a conductive polymer, or a block copolymer
having together conjugated portion and non-conjugated portion.
[62] Emitting Laver (EML)
[63] Because a hole transporting and an electron transporting are occurred at the same
time in the emitting layer, the emitting layer has both p-type semiconductor property
and n-type semiconductor property. The emitting layer has an n-type emitting layer in
which the electron transporting is faster than the hole transporting, or a p-type emitting
layer in which the hole transporting is faster than the electron transporting.
[64] Because the electrons transporting is faster than the holes transporting in the n-type
emitting layer, the light is emitted at the interface between the hole transporting layer and the emitting layer. It would be better that the LUMO energy of the hole
transporting layer is greater than the LUMO energy of the emitting layer in order to have high luminescence efficiency. The n-type emitting iayer includes, but noi limited to, aluminum (ris(8-hydroxyquinoline) (Alq ); 8-hydroxy-quinoline berillyum (BAlq); benzoxazole compound, benzothiazole compound, or benzimidazol compound; polyfluorene compound; or sîlacyclopentadiene (silole).
[65] In the p-type emitting layer, the holes transport faster than electrons do, so (hat the
light is emitted at the interface between the electron transporting and emitling layer. Therefore, it would be better that HOMO energy of the electron transporting layer is lower (han the HOMO energy of (ne emitting layer in order to have high luminescence efficiency.
[66] The high luminescence efficiency obtained by changing the LUMO energy of the
hole transporting layer in the p-type emitting layer is less than that in the n-type
emitting layer. Therefore, the organic luminescence device having the p-type emitting
layer may have the NP junction between the n-type organic compound layer and the p-
type emitting layer without forming the hole injection layer and the hole transporting
layer. The p-type emitting layer includes, but not limited to, a carbazole compound, an
anihracene compound, a poly(phenylene vinylenes) (PPV), or a spiro compound.
[67] Electron Transporting Laver (ETU
[68] The electron transporting layer has a high electron mobility to easily receive and
transport electrons from/to the cathode and the emitting layer. The electron
transporting layer includes, but not limited to, aluminum tris(8-hydroxyquinoline) (Alq
), organic compound having Alq structure, flavone hydroxide-metal complex, or sila-
cyclopentadiene (silole).
[69] Cathode
[70] The calhode has low work function in order to easily inject electrons into the p-type
organic compound layer such as the hole transporting layer. The cathode includes, but
not limited to, metal, such as, magnesium, calcium, sodium, kalium, titanium, indium,
yittrium, lithium, gadolinium, aluminum, silver, ţin, and lead or alloy thereof; or
multiple structured materials such as UF/AI or LiO^/Al. The cathode can be formed of
the same material to the conductive layer of the anode. Alternatively, either the
cathode or the conductive layer of the anode may include a transparent material.
[71] Organic Solar Batterv
[72] Organic solar battery includes an anode, a cathode, and an organic thin film
disposed belween the anode and the cathode. The organic thin film includes a pluralily
of layers in order to improve the effectiveness and stability of the organic solar battery.
Fig. 6 shows an organic solar battery according to an exemplary embodiment of the
present invention.
[73] Referring to Fig. 6, an organic solar battery includes a substrate 41, an anode 42
having a conductive layer 42a and an n-type organic compound layer 42b disposed on the substrate 41, an electron donor layer 43 disposed on the n-type organic compound layer 42b, an electron acceptor layer 44 disposed on the electron donor layer 43, and a cathode 45 disposed on the electron acceptor layer 44. In response to a photon from an externai light, electrons and holes are generated between the electron donor layer 43 and the electron acceptor layer 44. The generated holes are transported to the anode 42 through the electron donor layer 43.
[74] The electron donor layer 43 is formed of a p-type organic compound. The organic
compound can be a combination of two or more compounds. Although not shown in
the figures, the organic solar battery according to another exemplary embodiment of
the present invention may further include additional organic thin films or omit any
organic thin film to simplify the processing steps. The organic solar battery may
further employ an organic compound having multiple functions to reduce the number
of the organic thin films.
[75] A convenţional solar battery transports holes to an anode through the HOMO
energy of an organic thin film such as an electron donor layer. Therefore, as the energy difference between the Fermi energy of the anode and the HOMO energy of the electron donor layer is smaller, the hole extraction is greater. The organic solar battery according to an exemplary embodiment of the present invention, however, includes the anode 42, having both the conductive layer 42a and the n-type organic compound layer 42b, to extract holes.
[76] The energy difference between the LUMO energy of the n-type organic compound
layer 42b and the Fermi energy of the conductive layer 42a is about 2eV or less. The energy difference between the LUMO energy of the n-type organic compound layer 42b and the HOMO energy of the p-type organic compound such as the electron donor layer 43 is about leV or less. An NP junction is formed between the n-type organic compound layer 42b and the electron donor layer 43, so that holes are easily extracted. The extracted holes are injected to the conductive layer 42a through the LUMO energy of the n-type organic compound layer 42b. Therefore, the conductive layer 42a can be formed of the materials having various Fermi energies, and the cathode 45 and the anode 42 can be formed of the same materials.
f77] The conductive layer 42a and cathode 45 of the organic solar battery can be formed
of the same materials for the conductive layer and cathode of the organic luminescence device. The same materials for the n-type organic compound layer of the organic lu­minescence device can form the n-type organic compound layer of the organic solar battery. The electron acceptor layer 44 can be formed of the materials for the electron transporting layer or n-type emitting layer of the organic luminescence device or a fullerene compound. The electron donor layer 43 can be formed of the materials for the
p-type hole transporting layer or p-type emitting layer of the organic luminescence
device, or a thiophene compound.
[78] Organic Transistor
f 79] Fig. 7 shows an organic transistor according (o an exemplary embodiment of the
present invention. Referring to Fig. 7, the organic transistor includes a substrate 61, a
source electrode 65, a drain electrode 66, a gate 62, an insulaling layer 63 disposed on
(ne gale 62 and the substrate 61, a p-type organic compound layer 64 disposed on the
• insulaling layer 63 and forming holes, and an n-type organic compound layer 67
disposed between the source electrode 65 and/or drain electrode 66 and the p-type
organic compound layer 64. The energy difference between the LUMO energy of the
n-lypc organic compound layer 67 and the Fermi energy of the source electrode 65 or
the drain electrode 66 is about 2eV or less. The energy difference between the LUMO
cncrgy of (he n-type organic compound layer 67 and the HOMO energy of the p-type
organic compound layer 64 is about leV or less.
[80] The n-iyne organic compound layer 67 can extract the holes from the source
clcclrodc 65 and inject them to the drain electrode 66 via the LUMO energy of the n-typc organic compound layer 67. Because the NP junction is formed between the n-lypc organic compound layer 67 and the p-type organic compound layer 64, the holes arc cusily Iransported between the source electrode 65 and the drain electrode 66. The n-lypc organic compound layer 67 can form a portion of the source electrode 65 or the drain clcclrode 66, according to another exemplary embodiment of the present invcniion. In this case, the materials having various Fermi energies can form the source clcclrodc 65 or the drain electrode 66.
[81J The n-(ypc organic compound layer 67 can be formed of the same materials for the
n-lypc organic compound layer of the organic luminescence device, according to an
exemplary embodiment of the present invention. The gate 62 can be formed of the
same maicrials for the anode or cathode of the organic luminescence device. The
sourcc clcclrodc 65 or the drain electrode 66 can be formed of the same materials for
the anodc ol ihc organic luminescence device. The p-type organic compound layer 64
includc.s, hui not limited to, a pentaeene compound, an antradithiophene compound, a
hcn/odiihiophcnc compound, thiophene oligomers, polythiophenes, mixed-subunit
thiophcnc oligomers, or oxy-funcionalized thiophene oligomers. The insulating layer
63 can hc formed of silicon oxide, or silicon nitride; or a polymer, such as, polyimide,
Poly(2-vinylpyridine), Poly(4-vinylphenol), or poly (methylmetacrylale).
[82] Various aspccts and features of the present invention will be further discussed in
tcrms ol thc cxamples. The following examples are intended to illustrate various aspccis and fcatures of the present invention, but not to limited the scope of the present invcniion.
Example 1:
[84] Determination of HOMO and LUMO energies of HAT with UPS and UV-VIS
absorpţjop
[85] Hexanitrile hexaazatriphenylene (HAT) was used for an organic compound having
n-type semiconductor property. The HOMO energy of the HAT was determined by Ul­
traviolet Photoelectron Spectroscopy (UPS) in which the Vacuum U V line (about
2J.20eV) emitted from a Helium lamp was illustrated to a sample under an ultra high
vacuum (<10 ' Torr) and the kinetic energy of the electrons emitted from the sample
was examined.
[86] With the UPS, the work function of metals and the ionization energy (HOMO
energy and Fermi energy) of organic compounds were determined, respecţi vely. The
kinetic energy of the emitted electrons was the energy difference between the electron
binding energy of the sample and the vacuum UV energy (about 21.2 eV). Therefore,
the distribution of the binding energy of the materials contained in the sample was
determined by analyzing the distribution of the kinetic energy of the emitted electrons.
When the kinetic energy of the emitted electrons hâd a maximum value, the binding
energy of the sample hâd a minimum value. The minimum value of the binding energy
was used in deterrnining the work function (Fermi energy) and the HOMO energy of
the sample.
[87] The work function of gold was determined by using a gold film. The HAT was
vacuum deposited to the gold film, and the HOMO energy of the HAT was determined
by analyzing the kinetic energy of the electrons emitted from the HAT. Fig. 10 is a
graph showing UPS data of the gold film and ihe HAT film disposed on the gold film.
H, Ishii, el al„ Advanced Materials, J J, 605-625 (J 999). The HAT film has a thickness
of 20nm.
[88] Referring Io Fig. 10, an X-axis indicates the binding energy (eV), which was
determined, with respect to the work function of the gold film. The work function of
the gold was about 5.28eV, which was calculated by subtracting the maximum value
(about 15.92eV) of the binding energy from the energy (about 21.20eV) of the light il­
lustrated io the Au film. The HOMO energy of the HAT film was about 9.78eV, which
was calculated by subtracting the difference between the minimum value (about
3.79eV) and (he maximum value (about 15.21eV) of the binding energy from the light
energy (aboul 21.20eV). The Fermi energy of Ihe HAT film is aboul 6.02V.
[89] Another UV-VIS spectrum was taken with the organic compound, which was
formed by vacuum deposition of the HAT on a surface of a glass. The absorption edge was analyzed, and Ihe bând gap was determined to be about 3.26eV. Therefore, the LUMO energy of the HAT was about 6.54eV, which could be changed by an exciton binding energy. Because the HOMO energy of about 6.54eV was greater than the
Fermi energy of about 6.02eV, the exciton binding energy hâd to have about 0.52eV or
more so that the LUMO energy was less than the Fermi energy. The exciton binding
energy of an organic compound generally would be about 0.5 e V to about leV, and
thus the LUMO energy of the HAT would be about 5.54 to 6.02 eV.
[90] ExampJe 2:
[91] Hole injection characteristic of HAT
[92] A glass substrate coated with the ITO having a thickness of 1000Â was ultrasonic
washed for thirty minutes in a distilled water in which a detergent was melted. Corning
7059 glass was used as the glass substrate, and the product 15-333-55 manufactured by
Fischer Co. was used as the detergent. The glass substrate was further ultrasonically
washed in the distilled water for ten minutes, which was repeated twice.
[93] After washing, the glass substrate was sequentially ultrasonic washed for one
minute in an isopropyl alcohol solvent, an acetone solvent, and a methanol solvent, and
then dried. Then, the ITO coated glass substrate was treated by plasma for five minutes
in a plasma cleaner by using nitrogen under a pressure of about 14mtorr and a power of
about 50W. As a result, the work function of ITO was about 4.8 eV.
[94] The HAT of about 100Â was thermally deposiled on the ITO electrode under
vacuum to form an anode having an ITO conductive layer and an HAT n-type organic
compound layer. Then, the 4,4'-bis[N-(l-naphthyl)-N-phenylamino]biphenyl (NPB)
having a thickness of about 1500 Â, and the aluminum having a thickness of about 500
 were sequentially vacuum-deposited to form a p-type hole transporting layer and a
cathode, respectively. The result device was called 'device A'. The vacuum deposition
rates of the organic compounds and the aluminum were about 0.4 to 0.7 Â/sec and
about 2 Â/sec, respectively. The vacuum level of the vacuum deposition was about
2xI07to5xlO"storr.
[95] Comparative Exatnple l
[96] A 'device B' was fabricated in the same manner as in Example 2 except for the
absence of the HAT n-type organic compound layer. Fig. 11 is a graph showing current-voltage characteristics of the devices A and B of Example 2 and Comparative Example l, respectively. Referring to Fig. 11, at the DC bias voltage of about 6V, the current density of the device A is about 40mA/cm2 or more, but the current density of
l ")
the device B is about 10 mA/cm" or less.
[97] Because the work function (about 4.8eV) of the ITO conductive layer was less than
the LUMO energy (about 5.54 to 6.02eV) of the HAT n-type organic compound layer, which was disposed between the NPB layer and the ITO conductive layer, the electrons transported from the ITO conductive layer to the HAT n-type organic compound layer, and then VL was changed as shown in Fig. l (b). Therefore, the energy barrier between the ITO conductive layer and the HAT n-type organic
compound layer was lowered, and the holes transported to the NPB layer through the
electron transporting from the HOMO energy (about 5.4eV) of the NPB layer to the
LUMO energy (about 5.54 to 6.02eV) of the HAT n-type organic compound layer.
Therefore, the device A has higher current density at a predelenTlined voltage or more.
[98] The device B, however, hâd a certain energy barrier for inserting holes betwecn the
work function (about 4.8eV) of the ITO conductive layer and the HOMO energy
(about 5.4eV) of the NPB layer. Therefore, the current density in the device B did noi
increase even if higher voltage was applied to the device B.
[99] Example 3
[ 100] A glass substrate such as Corning 7059 glass was ultrasonically washed in a
distilled water in which a detergent was dissolved. The product manufactured by
Fischer Co. was used as the detergent, and the distilled water was twice filtered with
the filter manufactured by Millipore Co. After washing the glass substrate for thirty
minutes, the glass substrate was further ultrasonic washed in the distilled water for ten
minutes, which was repeated twice.
[101] After washing, the glass substrate was sequentially ultrasonically washed in an
isopropyl alcohol solvent, an acetone solvent, and a methanol solvent, and then dried, Then, the Al having a thickness of about 500Â was vacuum deposited on the glass substrate, and the HAT having a thickness of about 100 Â was heat and vacuum deposited on the Al conductive layer, thereby forming the anode having the Al conduclive layer and the HAT n-type organic compound layer. Then, the 4,4'-bis[N-(l-naphthyl)-N-phenylamino]biphenyl (NPB) compound having a thickness of about 1500 Â, and the alurninum having a thickness of about 500 Â were se­quentially heat and vacuum deposited to form a p-type hole transporting layer and a cathode, respectively.
[J 02] The result device was called 'device C'. The vacuum deposition rates of the organic
compounds and the aluminum were about 0.4 to 0.7 Â/sec and about 2 Â/sec, re-
7 8
spectively. The vacuum level of the vacuum deposition was about 2x10 to 5x10" torr.
[103] Comparative Exampje 2
[104] A 'device D' was fabricated in the same manner as in Example 3 except for the
absence of the HAT n-type organic compound layer. Fig. 12 is a graph showing current-voltage characteristics of the device C and D of Example 3 and Comparative Example 2, respectively. Referring to Fig. 12, at the DC bias voltage of about 6V, the currenl density of the device C was about 20mA/crrf or more, but the currenl density of the device D was about 10 mA/cm or less.
[105] Although the work function (about 4.2eV) of the Al was lower than that (4.8eV) of
the ITO, the turn-on voltage of the device C was not changed, and the current density was increased as the voltage reached at a certain value. On the contrary, the device D
showed a poor current-voltage characteristic, as shown in the device B. Therefore, the VL was changed in proporţionale to the changing of the work function of the ITO or Al conductive layer, and the energy barrier for hole injection or hole extraction hetween the conductive layer and the NPB p-type organic compound layer through the HAT n-type organic compound layer was not changed a lot.
[106] Example 4
1107] Organic luminescence device including an anode having an oxvgen plasma treated
ITO conductive layer and a HAT n-type organic compound layer
o
f 108] A glass substrate coated with the ITO having a thickness of about 1000A was
washed in the same manner as in Example 2. The ITO coated glass substrate was plasma treated for five minutes in a plasma cleaner by using an oxygen under a pressure of about 14mtorr and a power of about 50W. The work function of ITO was about 5.2 eV.
1109] The HAT of about 500Â was thermally deposited on the ITO under vacuum to form
a transparent anode having an ITO conductive layer and a HAT n-type organic compound layer. The HOMO energy of the HAT was about 9.78eV. Then, the 4,4'-bis[N-(l-naphthyl)-N-phenylamino]biphenyl (NPB) having a thickness of about 400Â and the HOMO energy of about 5.4eV was vacuum-deposited to form a p-type hole transporting layer. The Alq having the HOMO energy of about 5.7eV and the thickness of about 300 Â was vacuum-deposited on the p-type hole transporting layer to form an emitting layer.
[l 10] The chemical compound represented by Chemical Formula I, which hâd the HOMO
energy of about 5.7eV and the thickness of 200Â, was vacuum-deposited on the emitting layer to form an electron transporting layer.
[111] [Chemical Formula I]
(Figure Removed)
[112] The UF thin film having a thickness of about 12Â and the Al having a thickness of
about 2500Â were vacuum-deposited on the electron transporting layer to form a cathode. The vacuum deposition rates of the organic compounds, the UF, the Al were about 0.4 to 0.7 Â/sec, about 0.3 Â/sec, and about 2 Â/sec, respectively. The vacuum

level of the vacuum deposition was about 2x10 to 5x10 torr.

[113] Example 5
[114] Organic luminescence device including an anode having a nitrogen plasma treated
ITQ condyctive layer and a HAT n-tvpe organic compound layer
[115] The glass substrale was washed and plasma trealed in the same manner as in
Example 2. The ITO having a work function of about 4.8eV was formed on the glass substrate. The organic compound layer and the cathode were formed on the glass substrate on which the ITO conductive layer was formed in the same manner as in Example 4.
(116) Example 6
[117] Organic luminescence device including an anode having an Al conductive layer
and a HAT n-tvpe organic compound layer
[118] The glass substrate was prepared after washed in the same manner as in Example 3.
The Al having a thickness of about 100Â was vacuum deposited on the glass substrate.
The Al was semi-transparent and hâd work function of about 4.2eV. The organic
compound layer and the cathode were formed on the glass substrate on which the Al
conductive layer was formed in the same manner as in Example 4.
1119] Example 7
[120] Organic luminescence device including an anode having an Ag conductive layer
and a HAT n-type organic compound layer
[121] The glass substrate was prepared after washed in the same rnanner as in Example 3.
The Ag having a thickness of about 100Â was vacuum deposited on the glass
substrate. The Ag was semi-transparent and hâd work function of about 4.2eV. The
organic compound layer and the cathode were formed on the glass substrate on which
the Ag conductive layer was formed in the same manner as in Example 4.
[ 122] Fig. 13 is a graph showing current-voltage characteristics of the organic lu-
minescence devices of Examples 4 to 7. The conductive layers of the organic lu­minescence devices of Examples 4-7 hâd the work functions of about 5.2eV, about 4.8eV, about 4.2eV, and about 4.2eV, respecţively. Although the devices of Examples 4-7 hâd different work functions, the current-voltage characteristics thereof were similar to each other. Therefore, the current-voltage characteristics of the devices did not depend on the value of the work function.
[ 123] Table l shows the brightness of the devices of Examples 4-7, with respect to the
current density and the voltage. The devices of Examples 6 and 7, which hâd the Al and Ag conductive layers, respectively, hâd visible light transmission of less than about 30% and less than about 50%, respectively, which was lower than that (more than 80%) of the devices having the ITO conductive layer. Therefore, the brightness of the devices having the Al or Ag conductive layer would be equivalent to that of the devices having the ITO conductive layer in considering the visible light transmission rate.
(Figure Removed)
[1124] As shown in Table l, the holes were easily transported to (he hole transporting layer
through the LUMO energy of the n-type organic compound layer. When the LUMO
energy of the n-type organic compound layer hâd about 5.54 to 6.02eV and the energy
difference between the LUMO energy of the n-type organic compound layer and the
work function of the conductive layer was about 2eV or less, the current-voltage char-
acteristics of the organic luminescence devices were independent from the value of the
work function of the conductive layer. The energy differences between the LUMO
energy of the n-type organic compound layer and the work function of the conductive
layer in the devices of Examples 4 to 7 were about 0.24 to 0.82eV, about 0.64 to
1.22eV, about 1.24 to 1.82eV, and about 1.24 to 1.82eV, respecţively.
[125] Example 8
[126] Organic luminescence device including an Al conductive layer and a HAT n-type
organic compound layer
[ 127J A glass substrale was prepared in the same manner as in Example 3. The Al having
a thickness of about 100Â was vacuum dcposited on the glass substratc. The Al was semi-transparent and hâd the work function of about 4.2eV. The HAT having the HOMO energy of about 9.78eV and the thickness of about 500Â were heat and vacuum deposited on the glass substrate, on which the Al conductive layer was formed, to form the anode having the Al conductive layer and the HAT n-type organic compound layer.
[128] Then, the 4,4'-bis[N-(l-naphthyl)-N-phenylamino]biphenyl (NPB) having a
thickness of about 600 Â and the HOMO energy of about 5.46eV was vacuum
deposited to form a p-type hole transporting layer. The Alq having the HOMO energy
of about 5.62eV and the thickness of about 300Â was vacuum deposited on the hole
transporting layer to form an electron transporting and emitting layer. The LiF thin
film having a thickness of about 12 Â and the Al having a thickness of about 2500A
were sequentially vacuum deposited on the electron transporting and emitting layer to
form a cathode.
[ 129] The vacuum deposition rates of the organic compounds, LiF, and the aluminum were about 0.4 to 0.7 Â/sec, about 0.3 Â/sec, and about l -2 Â/sec, respectively. The vacuum level of the vacuum deposition was about 2x107 to 5xlO~8torr.
[130] Comparative Exarnple 3
[131] A glass substrale was prepared in the same manner as in Example 3. The Al having
a thickness of about 100Â was vacuum deposited on the glass substrale (o form an Al conductivc layer. The Al was semi-transparent and hâd work function of about 4.2eV. The copper phthalocyanine (CuPc) having the HOMO energy of about 5.20eV and the thickness of about 150Â was heat and vacuum deposited on the glass substrate, on which the Al conductive layer was formed, to form a hole injection layer.
[132] Then, the 4,4'-bis[N-(l-naphthyl)-N-phenylamino]biphenyl (NPB) having a
thickness of about 600 Â and the HOMO energy of about 5.46eV was vacuum deposited to form a p-type hole transporting layer. The Alq having the HOMO energy of about 5.62eV and the thickness of about 300Â was vacuum deposited on the hole transporting layer to form an electron transporting and emitting layer. The LiF thin film having a thickness of about 12 Â and the Al having a thickness of about 2500Â were sequentially vacuum deposited on the electron transporting and emitting layer to form a cathode.
[ 133] The vacuum deposition rates of the organic compounds, the LiF, and the aluminum
were about 0.4 to 0.7 Â/sec, about 0.3 Â/sec, and about l -2 Â/sec, respectively. The
vacuum level of the vacuum deposition was about 2x10 to 5x10 torr.
[134] Comparative Example 4
[135] An organic luminescence device was fabricated in the same manner as in
Comparative Example 3 except for the absence of forming the CuPc hole injection layer. The work function of the conductive material of Example 8 and the work function of the anodes of the Comparative Exarnples 3-4 were the same, (hat is, about 4.2eV.
[ 136] The device of Example 8 used the HAT having electron affinity as the n-type
organic compound layer of the anode, while the devices of Comparative Examples 3-4 did not have the n-type organic compound layer in the anodes thereof. Fig. 14 is a graph showing currenl-voltage characteristics of Example 8 and Comparative Examples 3-4.
[ 137] Referring to Fig. 14, the device of Example 8 showed an increased current density
at about 5 V, while the devices of the Comparative Examples 3-4 showed no increased current density at about 5 V. Table 2 shows brightness of the devices of ExampleS and (TableRemoved)
[138] As shown in Table 2, the device of Example 8, in which the anode included the Al
conductive layer and the HAT n-type organic compound layer, showed higher
brightness at a low voltage, while the devices of (he Comparative Examples 3-4, in
which the anode only included the conductive layer, showed much lower brightness at
the same voltage. This was because the energy barrier between the Al conductive layer
and the CuPc hole injection layer was too big to inject holes in the devices of
Comparative Examples 3-4.
(139) Example 9
[140] Organic luminescence device including an anode having an ITO conductive layer
and a F4TCNQ n-type organic compound layer
[ 141] A glass substrate including ITOconductive layer having work function of about
4.8eV was prepared in the same manner as in Example 2. The F4TCNQ having the LUMO energy of about 5.24eV and the thickness of about 360Â was vacuum deposited on the glass substrate, on which the ITO conductive layer was formed. Therefore, an anode was formed.
[142] Then, the 4,4'-bis[N-(l-naphthyl)-N-phenylamino]biphenyl (NPB) having a
thickness of about 400Â and the HOMO energy of about 5.46eV was vacuum deposited to form a p-typc hole transporling layer. The Alq having the HOMO energy of about 5.62eV and the thickness of about 500Â was vacuum deposited on the hole transporting layer to form an electron transporting and emitting layer. The LiF thin film having a thickness of about 12 Â and the Al having a thickness of about 2500Â were sequentially vacuum deposited on the electron transporting and emitting layer to form a cathode.
f 143] The vacuum deposition rales of the organic compounds, the LiF, and, the Al were
about 0.4 to 0.7 Â/sec, about 0.3 Â/sec, and about 1-2 Â/sec, respectively. The vacuum
7 Q
level of the vacuum deposition was about 2x10" to 5x10" torr. When a forward electric field of about 8 V was applied to a portion between the anode and the cathode of the device of Example 9, the current density of the device was about 198mA/cm~. The green-luminescence of Alq was observed through the anode having the ITO conductive layer and the F4TCNQ n-type organic compound layer.
[144] Example 10
[145] Organic luminescence including an anode having an Al conductive laver and a
F4TCNQ n-ţvpe organic compound layer
[146] A glass substrate was prepared in the same manner as in Example 3. The Al having
a thickness of about 100Â and a work function ofabout 4.2eV was vacuum deposited
on the glass substrale to form the conductive layer of the anode. The Al was semi-
transparent. The F4TCNQ was formed on the Al conductive layer to form the anode
having the AI conductive layer and the F4TCNQ n-type organic compound layer in the
same manner as in Example 9. Then, a hole transporting layer, an electron transporting
layer, and an emitting layer were formed sequentially, as described in Example 9.
(147] When a forward electric field of about 8V was applied (o a portion between the
anode and the cathode of the device of Example 9, the current density of the device was about J90mA/cm~. The green-luminescence of Alq was observed through the anode having the Al conductive layer and the F4TCNQ n-type organic compound layer. Although the work function of the conductive layer of Example 10 was different from that of Example 9, the green-luminescence was also observed in the device of Example 10.
(148] Comparative Example 5
[ J 49] An organic luminescence device was fabricated in the same manner as in Example
9 except for forming an anode having ITO/Alq , rather than an anode having ITO/
F4TCNQ. That is, the Alq^ having the LUMO energy of about 2.85eV and a (hickness
of 500 Â was formed on the ITO conductive layer.
[ 150] When a forward electric field of about 8V was applied to at an interface between
the anode and the cathode of the device of Comparative Example 5, the current density of the device was about 10 "mA/cm2. The green-luminescence of Alq was not observed.
f 151 ] The electrons or holes were not formed at the interface between the Alq and NPB
hole transporting layer, because the energy difference (about 2.61 e V) between the
LUMO energy (about 2.85eV) of Alq and the HOMO energy (about 5.46eV) of the
NPB hole transporting layer was too big. On the contrary, the devices of Examples 9
and 10 in which the anode included the F4TCNQ n-type organic compound layer and
the ITO or Al conductive layer, showed high brightness. In the devices of the
Examples 9 and 10, the energy difference between the Fermi energy (about 4.8eV) of
the ITO conductive layer or the work function (about 4.2eV) of the Al conductive layer
and the LUMO energy (about 5.24eV) of the F4TCNQ n-type organic compound layer
was about 0.44eV to 1.04eV and the energy difference between the HOMO energy of
the NPB hole transporting layer and the LUMO energy (about 5.24eV) of the F4TCNQ
n-type organic compound layer was about 0.22eV.
[152] Example 11
[153] Organic Solar Batterv
[154] A glass substrate coated with ITO having a thickness of about 1000Â was ultra-
sonîcally washed for thirty minutes in a distilled water in which a detergent was
melted. Corning 7059 glass was used as the glass substrate, and the product 15-333-55
mânuiactured by Fischer Co. was used as the detergent. Then, the glass substrate was
further ultrasonically washed in the distilled water for five minutes, which was
repeated (wice.
f 155] After washing, the glass substrate was sequentially ultrasonically washed in an
isopropyl alcohol solvent, an acetone solvent, and a methanol solvent, and then dried. Then, (he ITO coated glass subslrate was treated by plasma for five minutes in a plasma cleaner by using nitrogen plasma under a pressure of about 14mtorr and a power of about 50W. The work function of ITO was 4.8 e V.
[ 156] The HAT of about 200Â was thermally deposited on the ITO transparent electrode
under vacuum to form an anode having an ITO conductive layer and a HAT n-type organic compound layer. Then, the CuPc having a thickness of about 400 Â and a HOMO energy of about 5.20eV was vacuum-deposited to form a p-type electrons donor layer.
1157] A fullerene (C ) having a thickness of about 400Â, a HOMO energy of about
6.20eV and a LUMO energy of about 4.50eV was vacuum deposited on the p-type electron donor layer to form an electron accepter layer. The
2,9-dimethyl-4,7-diphenyl-l,10-phenanthroline (BCP) having a thickness of about 100
Â, a HOMO energy of about 7.00eV, and a LUMO energy of about 3.50eV was
vacuum deposited on the electron acceptor layer to form an exciton blocking layer. The
exciton blocking layer improved the effectiveness of an organic solar battery.
[158] The LiF having a thickness of about 5 Â and the Al having a thickness of about
2500 Â were sequentially vacuum deposited on the exciton blocking layer to form a
cathode. The vacuum deposition rates of the organic compounds, the LiF, and the Al
were about 0.4 to 0.7 Â/sec, about 0.3v/sec, and about 2 Â/sec, respectively. The
vacuum level of the vacuum deposition was about 2x10 to 5x10 torr.
[159] The l-V curve of the solar battery was measured by illustrating the light emitted
from Xenon lamp to the solar battery, and the efficiency of the solar battery was
measured by using the I-V curve. The efficiency of the solar battery was calculated by
dividing (he maximum multiplication values of the current and the voltage by the
energy value of the illustrated light. The solar battery of the Example 11 hâd an
efficiency of about 0.36%.
[160] Example 12
[161] Organic Solar Battery
[162] An organic solar battery was fabricated in the same manner as in Example 11
except for depositing the HAT n-type organic compound layer having a thickness of about 400 Ă. The solar battery of Example 12 hâd an efficiency of about 0.45%.
[163] Comparative Example 6
f 164] An organic solar battery was fabricated in the manner as in Example 11 except for
(he absence of the HAT n-type organic compound layer. The solar battery of Comparative Example 6 showed an efficiency of about 0.04%. The organic solar batlcries of Examples 11 and 12, in which the anode included both the ITO conductive layer and the HAT n-type organic compound layer, showed a high efficiency, while the organic solar battery of Comparative Example 6, in which the anode included only the ITO conductive layer, showed a low efficiency.
[165] Whilc (he disclosure has been described with reference to exemplary embodiments,
ii will hc understood by those skilled in the art that various changes may be made and cquivalcnts may be substituted forelements thereof without departing from the scope of (hc disclosure. In addition, many modifications may be made to adapt a particular silualion or material to the teachings of the disclosure without departing from the csscniial scope thereof. Therefore, it is intended that the disclosure not be limited to a particular cmbodiment disclosed as the best mode contemplated for carrying out this disclosurc, but that the disclosure will include all embodiments falling within the scope of (hc appcnded claims.
Industrial Applicability
[ 166] Elccironic devices according to exemplary embodiments of the present invention
include an n-(ype organic compound layer in addition to a conductive layer as an clccmxlc for hole injection or hole extraction. The n-type organic compound layer is chosen so (hat (he energy difference between the LUMO energy of the n-type organic compound layer and the Fermi energy of the conductive layer which contacts one side ol (hc n-lypc organic compound layer is about 2eV or less and the energy difference bciwcen (hc LUMO energy of the n-type organic compound layer and the HOMO energy ol (hc p-type organic compound layer which contacts the other side of the n-(ypc organic compound layer is about leV or less. Because the n-type organic compound layer lowers the energy barriers for hole injection or hole extraction and forms an NP junction between the n-type organic compound layer and the p-type organic compound layer, the electronic devices can use various malerials as electrodes, (hcrcby simplifying a process and improving efficiency.

Claims
[ l ] An electronic device comprising:
a first electrode to inject or extract hole, the first electrode including a conductive layer and an n-type organic compound layer disposed on the conductive layer; a second electrode to inject or extract electron; and
a p-type organic compound layer disposed between the conduclive layer of the
firsi electrode and the second electrode, the p-type organic compound layer
forming an NP junction between the n-type organic compound layer of the first
electrode and the p-type organic compound layer, "^
wherein an energy difference between a lowest unoccupied molecular orbital (LUMO) energy of the n-type organic compound layer of the first electrode and a Fermi energy of the conductive layer of the first electrode is about 2eV or less; and
wherein an energy difference between the LUMO energy of the n-type organic
compound layer of the first electrode and a highest unoccupied molecular orbital
(HOMO) energy of the p-type organic compound layer is about leV or less.
[2] The electronic device of claim l, wherein the p-type organic compound layer
comprises a hole injection layer, a hole transporting layer, or an emitting layer.
[3] The electronic device of claim l, further comprising at least one organic
compound layer disposed between the p-type organic compound layer and the second electrode,
wherein the at least one organic compound layer includes a hole transporting layer, an emitting layer, or an electron transporting layer.
[4] The electronic device of claim l, wherein the n-type organic compound layer of
the first electrode comprises
2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane(F4TCNQ), fluoro-
substituted 3,4,9,10-Perylenetetracarboxylic dianhydride (PTCDA), cyano-
substituted PTCDA, naphthalene-tetracaboxylic-dianhydride (NTCDA), fluoro-
substituted NTCDA, cyano-subslituted NTCDA, or hexanitrile hexaazat-
riphenylene (HAT).
[5 ] The electronic device of claim l, wherein the conductive layer of the first
electrode comprises metal, metal oxide, or a conductive polymer.
[6] The electronic device of claim l, wherein the conductive layer of the first
electrode and the second electrodes are formed of the same material.
[7 j An organic luminescence device comprising:
an anode including a conductive layer and an n-type organic compound layer disposed on the conductive layer;
a cathode; and
a p-type organic compound layer disposed between the conductive layer of the anode and the cathode, the p-type organic compound layer forming an NP junction between the n-type organic compound layer of the anode and the p-type organic compound layer,
wherein an energy difference between a LUMO energy of the n-type organic compound layer of the anode and a Fermi energy of the conductive layer of the anode is about 2eV or less; and
wherein an energy difference between the LUMO energy of the n-type organic compound layer of the anode and a HOMO energy of the p-type organic compound layer is about le V or less.
[8] The organic luminescence device according to claim 7, wherein the p-type
organic compound layer comprises a p-type hole injection layer; and wherein the organic luminescence device further comprises at least one organic compound layer disposed between the p-type hole injection layer and the cathode.
f 9] The organic luminescence device according to claim 8, wherein the at least one
organic compound layer comprises a hole transporting layer disposed on the p-
type hole injection layer, an emitting layer disposed on the hole transporting
layer, or an electron transporting layer disposed on the emitting layer.
[10] The organic luminescence device according to claim 9, wherein the emitting
layer comprises an n-type emitting layer or a p-type emitting layer.
[11] The organic luminescence device according to claim 7, wherein the p-type
organic compound layer comprises a p-type hole transporting layer; and wherein the organic luminescence device further comprises at least one organic compound layer disposed between the p-type hole transporting layer and the cathode.
112] The organic luminescence device according to claim 11, wherein the at least one
organic compound layer comprises an emitting layer disposed on the p-type hole
transporting layer, or an electron transporting layer disposed on the emitting
layer.
[13] The organic luminescence device according to claim 12, wherein the emitting
layer comprises an n-type emitting layer or a p-type emitting layer.
[14] The organic luminescence device according to claim 7, wherein the p-type
organic compound layer comprises a p-type emitting layer; and wherein the organic luminescence device further comprises an organic compound layer disposed between the p-type emitting layer and the cathode, the organic compound layer including an electron transporting layer
[ 15] The organic luminescence device according to claim 7, wherein at least one of the conductive layer of the anode and the cathode comprises a transparent
material,
f 16] The organic luminescence device according to claim 7, wherein the conductive
layer of the anode and the cathode is forrned of the same material.
117] The organic luminescence device according to claim 7, wherein the n-type
organic compound layer comprises the LUMO energy of about 4 to 7 eV and an electron mobility of about 10"8cm2/Vs to 1cmWs or about 10~6cm2/Vs to 10-2cm2/ Vs.
[ J 8] The organic luminescence device according to claim 7, wherein the n-type
organic compound layer comprises
2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), fluoro-
suhstituted 3,4,9,10-peryleneletracarboxylic dianhydride (PTCDA), cyano-
substituted PTCDA, naphthalene-tetracaboxylic-dianhydride (NTCDA), fluoro-
suhstituted NTCDA, cyano-substituted NTCDA, or hexanitrile hexaazat-
riphcnylene (HAT).
[19] A stacked organic luminescence device comprising:
a plurality of repeating units each having the anode, the p-type organic compound layer, and the cathode of claim 7,
wherein the cathode of a repeating unit is connected to the anode of adjacent
repeating unit in serial.
[20] An organic solar battery comprising:
an anode including a conductive layer and an n-type organic compound layer disposed on the conductive layer; a calhode; and
an electron donor layer disposed between the conductive layer of (ne anode and the calhode, the electron donor layer including a p-type organic compound layer and forming an NP junction between the n-type organic compound layer of the anode and the p-type organic compound layer,
wherein an energy difference between a LUMO energy of the n-type organic compound layer of the anode and a Fermi energy of the conductive layer of the anode is about 2eV or less; and
wherein an energy difference between the LUMO energy of the n-type organic
compound layer of the anode and a HOMO energy of the p-type organic
compound layer is about leV or less.
[21 j The organic solar battery according to claim 20, further comprising an electron
acccptor disposed between the cathode and the electron donor layer.
[22] The organic solar battery according to claim 20, wherein the conductive layer of the anode and the cathode is forrned of the same material.
[123] The organic solar battery according (to claim 20, wherein the n-type organic
compound layer of (the anode comprises
2,3,5,6-telrafluoro-7,7,8,8-tetracyanoquinodimelhane (F4TCNQ), fluoro-substituted 3,4,9,10-perylenete(tracarboxylic dianhydride (PTCDA), cyano-substituted PTCDA, naphthalene-tetracaboxylic-dianhydride (NTCDA), fluoro-substituted NTCDA, cyano-substituted NTCDA, or hexanilrilc hexaazat-riphenylene (HAT).
[124] An organic transistor comprising:
a source eleclrode; a drain electrode; a gate;
an insulating layer disposed on the gate;
a p-type organic compound layer disposed on the insulaling layer; and an n-type organic compound layer disposed belween the source electrode or the drain electrode and the p-type organic compound layer, an NP junction being formed belween the n-type organic compound layer and the p-type organic compound layer,
wherein an energy difference between a LUMO energy of the n-type organic compound layer and a Fermi energy of the source electrode or the drain electrode is about 2eV or less; and
wherein an energy difference between the LUMO energy of the n-lype organic
compound layer and a HOMO energy of thc p-type organic compound layer is type
about leV or less.
[25] The organic transistor according to claim 24, wherein the n-type organic
compound layer comprises 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), fluoro-substituted 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), cyano-substituted PTCDA, naphthalene-tetracaboxylic-dianhydride (NTCDA), fluoro-substituted NTCDA, cyano-subslituted NTCDA, or hexanitrile hexaazatriphenylene (HAT).