Claims:We claim:

1. A composite semiconductor precursor solution to constitute an inorganic-organic composite semiconductor material is provided in a way that the composite semiconductor precursor solution is comprised of one or more inorganic metal salts and one or more organic polymers, wherein the one or more organic polymers show limited intermixing with inorganic semiconductor material or phase obtained upon thermal or photonic curing and allows high conductivity and high mobility electronic transport through Two-Dimensional (2D) percolating inorganic semiconductor material or phase.

2. The composite semiconductor precursor solution as claimed in 1, the inorganic semiconductor material or phase obtained upon thermal or photonic curing is metal oxides.

3. The composite semiconductor precursor solution as claimed in 1, wherein the one or more organic polymers that are added, should have a maximum limit of addition beyond which a complete breakdown of the 2D percolation through the inorganic semiconductor material or phase in the composite semiconductor material would take place.

4. The composite semiconductor precursor solution as claimed in 1, wherein the composite semiconductor precursor solution converts to the desired composite semiconductor material upon supply of external energy through either thermal annealing at suitable temperature or through photonic curing using chosen amount of photonic energy inputs.

5. The composite semiconductor precursor solution as claimed in 1, further comprises a suitable solvent and optionally an additive/viscosity modifier depending on fabrication method of the composite semiconductor material used.

6. The composite semiconductor precursor solution as claimed in 1, wherein the one or more inorganic metal salts selected from a group comprising nitrates, halides, acetates, acetyl acetonates of indium, tin, zinc, copper etc. or a mixture thereof.

7. The composite semiconductor precursor solution as claimed in 1, wherein an additional group of one or more metal salts can be added as electronic carrier suppressor and as dopant to the parent inorganic semiconductor material and can be chosen from a group comprising nitrates, halides, acetates, acetyl acetonates of gallium, aluminium, tungsten, silicon etc. or a mixture thereof.

8. The composite semiconductor precursor solution as claimed in 1, wherein the one or more organic polymers is associated with one or more properties selected from group comprising non-polarity, chemical inertness, insolubility/partially solubility and high melting/ decomposition temperature.

9. The composite semiconductor precursor solution as claimed in 1, wherein the one or more organic polymers is selected from a group comprising cellulose ethers, acrylic polymers, polypropylenes, polypropoxides or a mixture thereof.

10. The composite semiconductor precursor solution as claimed in 1, wherein the one or more organic polymers can be Ethyl cellulose (EC), Hydroxypropyl Methylcellulose (HPMC), Carboxymethyl cellulose (CMC), Polyvinyl acetate (PVA) or a mixture thereof.

11. The composite semiconductor precursor solution as claimed in 1, wherein the one or more inorganic metal salts are added maintaining a molarity of 0.01 M to 1 M in the chosen solvent.

12. A method for fabricating an electronic device using the composite semiconductor precursor solution as claimed in claim 1, the said method comprises –
solution-processing or printing of one or more layers of the composite semiconductor precursor solution in order to achieve an electronic device with simultaneous and desired admixture of electronic transport properties and mechanical strain tolerance.

13. The method as claimed in claim 12, the electronic device can be a field-effect transistor (FET) device where further device components, such as passive electrodes, comprising source, drain and gate, may either be solution-processed/ printed or grown using alternative chemical or Physical Vapour Deposition (PVD) methods and lithography, wherein gate dielectric/gate insulator of the electronic device may be chosen from an inorganic oxide dielectric, an inorganic ferroelectric, an organic dielectric, an organic ferroelectric and electrolytic insulator which may either be solution processed/printed or deposited using alternative chemical or physical vapour deposition methods and lithography.

14. The method as claimed in claim 12, wherein other flexible electronic devices may be fabricated by solution-processing/printing of the composite semiconductor solution such as Light Emitting Diodes (LEDs), photovoltaics, Photodiodes, UV-detectors, sensors, thermoelectrics and memories, wherein co-existence of superior electronic transport and mechanical strain tolerance is important in flexible electronic applications.

15. The method as claimed in claim 12, wherein the solution processing technique to fabricate the composite semiconductor material based device from the composite semiconductor precursor solution can be chosen from solution-processing techniques such as spin coating, dip coating, spray coating and bar coating, or jetting-type printing techniques such as inkjet printing, aerosol jet printing electrohydrodynamic jet printing or replication-type printing techniques such as gravure, reverse gravure, flexography, offset, screen printing and dry transfer/contact printing.

16. The method as claimed in claim 12, wherein the solution-processed/printed composite semiconductor precursor solution is converted to the composite semiconductor material by annealing at a pre-selected temperature which is sufficient to create the high mobility inorganic semiconductor phase however does not melt or fully decompose the one or more organic polymers, wherein the pre-selected annealing temperature can be between 150 °C to 400 °C.

17. The method as claimed in claim 12, wherein the solution-processed/printed composite semiconductor precursor solution is converted to the composite semiconductor material by photo-curing with a pre-selected incident energy dose which is sufficient to create the high mobility inorganic semiconductor phase however does not melt or fully decompose the organic polymer(s).
, Description:TECHNICAL FIELD
The present disclosure relates to the field of semiconductors, material science, device physics and electronics. Particularly, the present disclosure discloses compositions of a composite semiconductor precursor solution and a method for fabricating an electronic device using the composite semiconductor precursor solution.

BACKGROUND
Printed electronics had initially been conceptualized around Organic Semiconductors (OS). However, due to their limited carrier mobility and environmental stability, the inorganic alternatives, especially solution-processed oxide semiconductors have recently been sought after. Oxide semiconductors can demonstrate largely superior electrical properties compared to organic semiconductors, and in fact, the solution processed/printed oxide semiconductors can very well match their performance with the physical vapor deposited ones. However, the primary drawback in the case of oxide semiconductors is their limited mechanical performance, bendability, strain tolerance etc., which may allow them to be used in curved displays, but not for truly flexible electronic applications.

Inorganic semiconducting oxides, with their inherent wide band gap ensuring optical transparency in visible spectrum, high electron mobility even when solution-processed, environmental stability, and most importantly easy adaptability to low-cost solution processing/printing, makes them widely suitable for volume production of Thin Film Transistors (TFTs) and logic electronics. In fact, oxide semiconductors are believed to be one of the most promising active materials for TFTs that can be used in state-of-the-art display technologies and in next-generation printed electronics. Although there are many growth techniques available for metal oxides, solution-processing may be ideally suitable for inexpensive and volume production of electronic devices. Presently, solution-processed oxide TFTs can nearly match the performance of the Physical Vapour Deposition (PVD)-grown counterparts. However, these ionic crystals lack the necessary mechanical reliability that would be of key importance for their widespread use in flexible electronic applications, or even for the roll-to-roll printing on flexible substrates.

Therefore, in case of solution-processed flexible electronics, it may be a challenge to obtain matching electrical and mechanical performance at the same time. Here, attempts have been made to combine advantages of polymer and oxide semiconductors by fabricating polymer doped oxide TFTs. Here, the polymer doping typically frustrates crystal structure of the parent oxide material and causes amorphization. However, the polymer doping also degrades the device mobility rapidly, thereby limiting the possible extent of polymer addition to only small values, which may not be sufficient for any decisive enhancement in mechanical reliability.

In this regard, amorphous oxide semiconductors have earlier been introduced which can maintain very high mobility values, even when they are in amorphous state. Inspired from this, amorphous organic-inorganic hybrid semiconductor systems have been proposed (as mentioned above). However, only a small weight fraction of the organic polymer has been possible to be added without compromising the electrical properties of the hybrid semiconductor material, and beyond this nominal addition of the organic phase, the transport properties (electron mobility) are seen to deteriorate rapidly. However, this small amount of organic addition does not improve the mechanical performance to a large extent.

Notably, oxide semiconductors, especially indium oxide possess extremely robust electronic structure, which remains unperturbed to the addition of other elements, amorphization or substantial lattice strain. As a result, unlike amorphous silicon which show carrier mobility of only 0.5 cm2/Vs, amorphous Indium Gallium Zinc Oxide (IGZO) could emerge with device mobility values that are not substantially lower than the parent semiconductor material i.e., polycrystalline indium oxide. In fact, the uncompromised carrier mobility results from large spherical 5s orbital of indium oxide that is devoid of directionality and can offer band transport even in amorphous state of the semiconductor material. Now, having been encouraged by the success of IGZO, recently, amorphization of indium oxide has also been suggested with polymer doping. Identical to the addition of Ga and Zn, here small amounts of polymer have been found sufficient to suppress crystallinity of indium oxide. Electrically insulating polymers such as poly(4-vinylphenol) (PVP), different molecular weight of polysterene (PS), polyacrylamide, and electron donating polymer polyethylenimine (PEI) have been used as dopants. Notably, here the interest behind the polymer doping has not only been focussed at amorphization, but also aimed at imparting mechanical strain tolerance. However, an amount of polymer in the range of 1-2 wt.% may provide only limited advantage over the undoped indium oxide. In order to ascertain a decisive improvement in mechanical performance, a significantly larger amount of organic polymer addition would be essential, which is apparently not possible without comprising the carrier mobility of the semiconductor films.

The relevant references are appended here. Reference [1] provides an example of the said approach of chemical doping induced amorphization of In2O3 by use of an electrically insulating polymer poly(4-vinylphenol) (PVP). However, as the PVP concentration is increased, the electron mobility of the PVP-doped In2O3 TFTs shows a rapid fall in carrier mobility values. This fall in mobility can be attributed to the charge trapping by PVP thus degrading the electron mobility.

In a similar approach, polyethylenimine (PEI) was added as a dopant to In2O3 as explained in references [2] and [3]. An increase in the concentration of PEI above 1.0 wt.% showed deterioration in the electron mobility from 9 cm2 V-1 s-1 (achieved with 1.0 wt.% PEI).
In reference [4], polyacrylamide was used as a polymer dopant for InOx TFTs, here an optimal concentration was 0.3 wt.% of the polymer, above which electron mobility started to gradually decrease even for the polymer concentration of 0.5 wt.%.

Therefore, the state-of-the-art calls for invention of new organic-inorganic composite semiconductor systems where a large extent of the polymer material can be added for a true enhancement in mechanical performance of the composite material, however, without comprising the electronic transport properties (carrier mobility values) of the inorganic semiconductor in it. Here the aim is to combine the advantage of high field-effect mobility and mechanical bendability and achieve both aspects simultaneously.

The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

SUMMARY
In an embodiment, the present disclosure relates to a composite semiconductor precursor solution to constitute an inorganic-organic composite semiconductor material. The composite semiconductor precursor solution is comprised of one or more inorganic metal salts and one or more organic polymers. The one or more organic polymers show limited intermixing with inorganic semiconductor material or phase obtained upon thermal or photonic curing and allows high conductivity and high mobility electronic transport through Two-Dimensional (2D) percolating inorganic semiconductor material or phase.

In an embodiment, the present disclosure relates to a method for fabricating a semiconductor device using the composite semiconductor precursor solution. The method comprises solution-processing or printing of one or more layers of the composite semiconductor precursor solution in order to achieve an electronic device with simultaneous and desired admixture of electronic transport properties and mechanical strain tolerance.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and/or methods in accordance with embodiments of the present subject matter are now described, by way of example only, and regarding the accompanying figures, in which:

Figure 1 shows XRD pattern of printed indium oxide films with 0, 10, 25, 40 and 50 wt.% ethyl cellulose (EC) and 10 wt.% each of polyvinyl acetate (PVA), hydroxypropyl methylcellulose (HPMC) content in a composite semiconductor precursor solution with respect to the weight of indium nitrate;

Figure 2a shows TEM images of the inkjet-printed pure In2O3 films;

Figure 2b shows TEM images of the inkjet-printed In2O3 with 25 wt.% EC films;

Figures 3a, 3b, 3c, 3d, 3e, 3f, 3g, and 3h illustrates transfer characteristics of TFTs with pristine In2O3, 10 wt.% EC, 25 wt.% EC, 40 wt.% EC, 10 wt.% PVA, 10 wt.% HPMC, 10 wt.% PEI and 10 wt.% PVP based composite semiconductor, respectively, printed on substrates of ITO coated glass;
Figure 4 shows the average width-normalized On-currents, ID,ON/W (extracted from VDS= 1.0 V) and average width-normalized transconductance (gm/W), the average threshold voltage (VT) and average linear mobility (µlin) of In2O3 FETs on ITO coated glass substrate with varied concentrations (0, 10, 25, 40, 50) wt.% of the added polymer ethyl cellulose (EC), and with 10 wt.% each of polyvinyl acetate (PVA), hydroxypropyl methylcellulose (HPMC), polyethylenimine (PEI) and poly(4-vinylphenol) (PVP). Hollow and solid spheres represented in the top half show the average of ID,ON/W and gm/W, respectively and the hollow and solid squares represented in the bottom half show the average of VT and µlin, respectively;
Figures 5a and 5b show statistics of transfer characteristics of In2O3 FETs with No EC inkjet-printed on substrates of Kapton at a varying VDS of 0.5 V and 1.0 V;

Figures 5c and 5d show statistics of transfer characteristics of In2O3 FETs with 25 wt.% EC inkjet-printed on substrates of Kapton at a varying VDS of 0.5 V and 1.0 V;

Figures 6a and 6b shows transfer curves for FETs with no EC, subjected to bending fatigue test (tension) routine with different bending radii of infinity, 5 mm, 2.5 mm, and 1.5 mm (100 cycles at every bending radius), respectively at a varying VDS of 0.5 V and 1.0 V; ;

Figure 6c and 6d show transfer curves of FETs with 25 wt.% EC in the composite semiconductor precursor solution, subjected to bending fatigue test (tension) routine with different bending radii of infinity, 5 mm, 2.5 mm, and 1.5 mm (100 cycles at every bending radius), respectively at a varying VDS of 0.5 V and 1.0 V;

Figure 6e illustrates change in linear mobility of FETs with the bending fatigue tests performed at different bending radii;

Figure 7 shows SEM images of semiconductor channel before bending tests with No EC and 25 wt.% EC and the ones where the films are subjected consequently to a bending fatigue test (tension) with radii of 5 mm, 2.5 mm and 1.5 mm (100 cycles at every bending radius). Scale bars represent (a,d) 2 µm, (b,e) 5 µm and (c,f) 10 µm. The arrows represent the strain direction;

It should be appreciated by those skilled in the art that any block diagrams/illustrations herein represent conceptual views of illustrative systems embodying the principles of the present subject matter.

DETAILED DESCRIPTION
In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the disclosure.

The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device, or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or method.

The terms “includes”, “including”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device, or method that includes a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus proceeded by “includes… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or method.

In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

The present disclosure proposes a composite semiconductor precursor solution which comprised of one or more inorganic metal salts and one or more organic polymers. The composite semiconductor precursor solution may be used for fabrication of an electronic device. In an embodiment, the electronic device may be a Field-Effect Transistor (FET) device where further device components, such as passive electrodes, comprising source, drain and gate, may either be solution-processed/ printed or grown using alternative chemical or Physical Vapour Deposition (PVD) methods and lithography. The gate dielectric/gate insulator of the electronic device may be chosen from an inorganic oxide dielectric, an inorganic ferroelectric, an organic dielectric, an organic ferroelectric and electrolytic insulator which may either be solution processed/printed or deposited using alternative chemical or physical vapour deposition methods and lithography. In an embodiment, the electronic device may be a flexible electronic device. Such flexible electronic device may be fabricated by solution-processing/printing of the composite semiconductor precursor solution. In an embodiment, the flexible electronic device may be Light Emitting Diodes (LEDs), photovoltaics, Photodiodes, UV-detectors, sensors, thermo-electrics and memories. By using the composite semiconductor precursor solution, co-existence of superior electronic transport and mechanical strain tolerance is achieved in flexible electronic device and its applications.

Before describing the invention in detail, provided below are definitions of some terms that have been used throughout the present disclosure.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by a person skilled in the art to which this invention belongs. Although any methods and materials similar to or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described. A number of terms are defined and used throughout the specification with the following definitions provided for convenience.
The terms “an embodiment”, “embodiment”, “embodiments”, “the embodiment”, “the embodiments”, “one or more embodiments”, “some embodiments”, and “one embodiment” mean “one or more (but not all) embodiments of the invention(s)” unless expressly specified otherwise.

The terms “including”, “comprising”, “having” and variations thereof mean “including but not limited to”, unless expressly specified otherwise.

The enumerated listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise.

The terms “a”, “an” and “the” mean “one or more”, unless expressly specified otherwise.

A description of an embodiment with several components in communication with each other does not imply that all such components are required. On the contrary a variety of optional components are described to illustrate the wide variety of possible embodiments of the invention.
As used herein, the term “composite” is in the context of the components of the semiconductor precursor solution (also referred to as semiconductor precursor ink) of the present disclosure characterized by presence of at least two components, including at least one or more inorganic metal salts and at least one or more organic polymers. Accordingly, the phrases “composite semiconductor precursor solution”, “composite semiconductor precursor ink” and so on refer to a combination of inorganic component(s) that are typically simple or complex one or more inorganic metal salts and one or more organic polymers that can be a natural or synthetic polymer which or its partial or complete decomposition product would remain in the material composition post curing.
As used herein, the terms “composite semiconductor precursor solution”, “composite semiconductor precursor ink”, “semiconductor ink”, and so on have been used in alignment with the meaning of the said term in the field of semiconductors and electronics. Particularly, the composite semiconductor precursor solution in the present disclosure is a composition in liquid phase or a solution that is used for the fabrication of an electronic device with simultaneous and desired admixture of electronic transport properties and mechanical strain tolerance. In some embodiments, said composite semiconductor precursor solution of the present disclosure comprises inorganic metal salt(s), viscosity modifier(s), organic polymer(s) and solvent(s).

As used throughout the present disclosure, the term “metal salts” refers to substances consisting of one or more metal cations and non-metal anions formed by reaction of metal(s) with an acid where the metal cation replaces the H+ ion of the acid. Further, the term “inorganic metal salts” refer to metal salts which dissociate in solution with ions or electrolytes. Here, one or more inorganic metal salts can be selected from a group comprising nitrates, halides, acetates, acetyl acetonates of indium, tin, zinc, copper etc., or a mixture thereof.

As used throughout the present disclosure, the term “organic polymers” refers to polymers having an organic framework, which when added to the composite semiconductor precursor solution and subsequently heated to desired temperature, intermixes with the metal oxide phase only to a very limited extent, thereby allowing the crystalline metal oxide phase formation even when the organic polymer is present in the composite semiconductor precursor solution in a large amount, i.e. greater than 10 wt.%.

In some embodiments, the organic polymers is selected from a group Ethyl cellulose (EC), Hydroxypropyl Methylcellulose (HPMC), Carboxymethyl cellulose (CMC), Polyvinyl acetate (PVA) or a mixture thereof.

In some embodiments, the composite semiconductor precursor solution composition comprises the inorganic metal salt(s) at a concentration of about 0.01 Molar to about 5 Molar.

In some embodiments, the composite semiconductor precursor solution composition comprises the organic polymer(s) at a concentration of about 0.1 wt.% to about 20.0 wt.%.

In some embodiments, the composite semiconductor precursor solution composition comprises one or more solvent(s) at a concentration of about 40 wt.% to about 99.5 wt.%.

In some embodiments, the solvent is a combination of alcohol and deionized water, the composite semiconductor precursor solution composition comprises the alcohol at a concentration of about 20 wt.% to about 80 wt.% and the deionized water at a concentration of about 1.0 wt.% to about 50 wt.%.

In some embodiments, the solvent(s) is selected from a group comprising alcohol(s), water, acetates, carbonates, DMSO, DMF, acetonitrile or any combination thereof.

In some embodiments, the alcohol(s) is selected from a group comprising ethanol, 2-methoxy ethanol, propanol, butanol, ethylene glycol, isopropyl alcohol, methanol, propylene glycol, diethylene glycol, or any combination thereof.

In some embodiments, the water is selected from a group comprising deionized water (DI), distilled water, Milli-Q® water, double distilled water or any combination thereof.

In some embodiments, a viscosity modifier(s) is incorporated into the composite semiconductor precursor solution in order to adjust the viscosity of the composite semiconductor precursor solution. The viscosity modifier further helps to obtain a homogeneous and isotropic film over large area when the composite semiconductor precursor solution is put to application. Incorporation of water into the composite semiconductor precursor solution helps counterbalance hydrophobicity of surfaces to which the semiconductor ink is applied and further facilitates low temperature hydrolysis.

In some embodiments, the viscosity modifier(s) is selected from a group comprising Ethylene Glycol (EG), Diethylene Glycol (DEG), polyethylene glycol (PEG), glycerol, terpineol or any combination thereof.

In some embodiments, the composite semiconductor precursor solution composition comprises the viscosity modifier(s) at a concentration of about 0.1 wt.% to about 40 wt.%.

In an exemplary embodiment, the present disclosure provides a composite semiconductor precursor solution comprising indium nitrate, ethyl cellulose, ethylene glycol, ethanol and deionized water.

In said exemplary embodiment, the composite semiconductor precursor solution comprises the Indium nitrate at a concentration of about 0.1 wt.% to about 5 wt.%, the ethyl cellulose at a concentration of about 0.01 wt.% to about 5 wt.%, the ethylene glycol at a concentration of about 0.1 wt.% to about 20 wt.%, the ethanol at a concentration of about 10 wt.% to about 70 wt.% and deionized water at a concentration of about 1.0 wt.% to about 20 wt.%.

In an exemplary embodiment, the present disclosure provides a composite semiconductor precursor solution comprising indium nitrate, polyvinyl acetate, ethanol and deionized water.

In said exemplary embodiment, the composite semiconductor precursor solution comprises the Indium nitrate at a concentration of about 0.1 wt.% to about 5 wt.%, the polyvinyl acetate at a concentration of about 0.01 wt.% to about 5 wt.%, the ethanol at a concentration of about 10 wt.% to about 90 wt.% and deionized water at a concentration of about 10 wt.% to about 90 wt.%.

In an exemplary embodiment, the present disclosure provides a composite semiconductor precursor solution comprising indium nitrate, hydroxypropyl methyl cellulose, ethylene glycol, ethanol and deionized water.

In said exemplary embodiment, the composite semiconductor precursor solution comprises the Indium nitrate at a concentration of about 0.1 wt.% to about 5 wt.%, the hydroxypropyl methylcellulose at a concentration of about 0.01 wt.% to about 2 wt.%, the ethylene glycol at a concentration of about 0.1 wt.% to about 20 wt.%, the ethanol at a concentration of about 10 wt.% to about 70 wt.% and deionized water at a concentration of about 1.0 wt.% to about 20 wt.%.

In some embodiments, the substrate is selected from a group comprising polyimide, glass, Si wafer, textile, polyethylene terephthalate, polyethylene naphthalate. In some embodiments, the substrate is a lithographically patterned to obtain the passive electrodes. In some embodiments, the patterned substrate comprises passive electrodes of gold, ITO, silver or platinum which is structured on the surface of the substrate.

In some embodiments, the composite semiconductor precursor solution is dispensed on the substrate by any solution processing or printing technique.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. The use of the expression ‘at least’ or ‘at least one’ suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results. Numerical ranges stated in the form ‘from x to y’ include the values mentioned and those values that lie within the range of the respective measurement accuracy as known to the skilled person. If several preferred numerical ranges are stated in this form, of course, all the ranges formed by a combination of the different end points are also included.

The terms “about” or “approximately” as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, are meant to encompass variations of and from the specified value, such as variations of +/-10 wt.% or less, +/-5 wt.% or less, +/-1 wt.% or less, and +/-0.1 wt.% or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention. It is to be understood that the value to which the modifier “about” or “approximately” refers is itself also specifically, and preferably, disclosed.

As used herein, the terms “include” (any form of “include”, such as “include”), “have” (and “have”), “comprise” etc. any form of “having”, “including” (and any form of “including” such as “including”), “containing”, “comprising” or “comprises” are inclusive and will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

It is to be noted that the term “a” or “an” entity refers to one or more of that entity. As such, the terms “a” (or “an”), “one or more”, and “at least one” can be used interchangeably herein.
As regards the embodiments characterized in this specification, it is intended that each embodiment be read independently as well as in combination with another embodiment. For example, in case of an embodiment 1 reciting 3 alternatives A, B and C, an embodiment 2 reciting 3 alternatives D, E and F and an embodiment 3 reciting 3 alternatives G, H and I, it is to be understood that the specification unambiguously discloses embodiments corresponding to combinations A, D, G; A, D, H; A, D, I; A, E, G; A, E, H; A, E, I; A, F, G; A, F, H; A, F, I; B, D, G; B, D, H; B, D, I; B, E, G; B, E, H; B, E, I; B, F, G; B, F, H; B, F, I; C, D, G; C, D, H; C, D, I; C, E, G; C, E, H; C, E, I; C, F, G; C, F, H; C, F, I, unless specifically mentioned otherwise.

In some embodiment, one or more organic polymers in the composite semiconductor precursor solution show limited intermixing with inorganic semiconductor material or oxide phase obtained upon thermal or photonic curing and allows high conductivity and high mobility electronic transport through 2D percolating inorganic semiconductor material or phase. The one or more organic polymers are associated with one or more properties selected from group non-polarity, chemical inertness, insolubility/partially solubility and high melting/ decomposition temperature. The one or more polymers oppose large degree of intermixing at atomic level with the parent oxide, promote/allow its crystallization or to maintain its crystalline state and help to retain the electrical properties of the oxide semiconductors intact, even when they are in near-equal amounts.

In some embodiment, the one or more organic polymers do not participate in the hydrolysis reaction of the one or more inorganic metal salts and only nominally intermixes within the indium oxide crystal lattice. In fact, it is observed that the one or more organic polymers can promote crystallization at lower temperatures in otherwise amorphous pristine indium oxide parent material. In an embodiment, the one or more organic polymers is selected from a group comprising cellulose ethers, acrylic polymers, polypropylenes, polypropoxides or a mixture thereof. In an embodiment, the one or more organic polymers can be Ethyl cellulose (EC), Hydroxypropyl Methylcellulose (HPMC), Carboxymethyl cellulose (CMC), Polyvinyl acetate (PVA) or a mixture thereof. The one or more organic polymers must have a maximum limit of addition beyond which a complete breakdown of 2D percolation through the inorganic semiconductor material or phase in the composite semiconductor material would take place.

In an embodiment, the composite semiconductor precursor solution converts to the desired composite semiconductor material upon supply of external energy through either thermal annealing at suitable temperature or through photonic curing using chosen amount of photonic energy inputs. The inorganic semiconductor material or phase obtained upon thermal or photonic curing is metal oxides.

In an embodiment, the composite semiconductor precursor solution may include a suitable solvent and optionally an additive/viscosity modifier depending on fabrication method of the composite semiconductor material used. The one or more inorganic metal salts are selected from a group comprising nitrates, halides, acetates, acetyl acetonates of indium, tin, zinc, copper etc. or a mixture thereof. An additional group of one or more metal salts can be added as electronic carrier suppressor and as dopant to the parent inorganic semiconductor material and can be chosen from a group comprising nitrates, halides, acetates, acetyl acetonates of gallium, aluminium, tungsten, silicon etc. or a mixture thereof.
In an embodiment, the one or more inorganic metal salts are added maintaining a molarity of 0.01 M to 5 M in the chosen solvent.

In some embodiments, indium salt(s) is selected from a group comprising indium nitrate hydrate, indium chloride, indium chloride tetrahydrate, indium acetate, indium acetylacetonate, indium perchlorate hydrate, indium bromide, indium fluoride, indium iodide or any combination thereof.

In some embodiments, zinc salt(s) is selected from a group comprising zinc bromide, zinc bromide dihydrate, zinc chloride, zinc fluoride, zinc iodide, zinc nitrate hydrate, zinc oxalate hydrate, zinc perchlorate hexahydrate, zinc acetate, zinc acetylacetonate or any combination thereof.

In some embodiments, tin salt(s) is selected from a group comprising tin acetylacetonate, tin bromide, tin chloride, tin fluoride, tin iodide, tin acetate, tin nitrate or any combination thereof.

In some embodiments, copper salt(s) is selected from a group comprising copper bromide, copper chloride, copper chloride dihydrate, copper fluoride, copper iodide, copper nitrate hydrate, copper perchlorate hexahydrate, copper sulfate, copper acetate, copper acetylacetonate or any combination thereof.

In some embodiments, the gallium salt(s) is selected from a group comprising gallium bromide, gallium chloride, gallium iodide, gallium nitrate hydrate, gallium perchlorate hydrate, gallium sulfate, gallium sulfate hydrate, gallium acetylacetonate, gallium acetate or any combination thereof.

In an embodiment, the pristine semiconductor is amorphous upon annealing at 275 °C, however, the composite semiconductor turns crystalline with the addition of EC in the semiconductor precursor solution and remains highly crystalline even when the EC content exceeds the weight fraction of In2O3. On the other hand, an addition of up to 90 wt.% of EC with respect to In2O3 has resulted fairly unaltered electrical performance as compared to pristine In2O3 FETs. This is possible due to the fact that EC only weekly interacts with In2O3, and the resultant semiconductor is an organic/inorganic composite where the interconnected In2O3 nanocrystals maintain a percolating semiconductor film and the applied electric field (gate field) can penetrate the organic material to ensure carrier accumulation and high mobility TFT performance. As a result, extremely high polymer content in the resultant TFTs are found to be ultra-flexible and devoid of micro-cracks even after rigorous bending fatigue tests performed with bending radius down to 1.5 mm. This also is associated with unaltered electrical performance; in comparison to pristine In2O3 films that underwent the bending test. The pristine In2O3 cracked thoroughly and the devices mobility of the pristine In2O3 TFTs reduces by an order of magnitude.

Consequently, an unaltered estimated linear mobility of 90 cm2V-1s-1 can be obtained in In2O3 TFTs with near-equal weight of ‘Ethyl Cellulose’, which can survive rigorous bending fatigue tests down to 1.5 mm bending radius, without any deterioration in electrical performance and without formation of micro-cracks in the composite semiconductor material.

An exemplary method for preparing the composite semiconductor precursor solution is described. In an embodiment, the composite semiconductor precursor solution may be prepared by dissolving 0.1 M of indium (III) nitrate hydrate ([In(NO3)3.xH2O], 99.99 wt.%, trace metal basis, Sigma Aldrich CHEMIE GmbH) in ethanol. In addition, Ethylene Glycol (EG) and De-Ionized (DI) water was added in the ratio of ethanol: EG: DI= 1: 0.1: 0.2. The EG was added to adjust the viscosity of the ink and to obtain homogeneous and isotropic semiconductor film over large area. On the other hand, de-ionized water was added to counterbalance hydrophobicity of the polyimide substrates and to facilitate low temperature hydrolysis. This was the composition of the pristine In2O3 ink; in every other case, a certain amount of polymer is added to the ink. The weight percentage of the added polymer was calculated with respect to the amount of indium nitrate salt that was taken. For example, 10 wt.%, 25 wt.%, 40 wt.% and 50 wt.% EC would correspond to 6 mg, 15 mg, 24 mg and 30 mg of EC with respect to 60 mg of the indium nitrate in 2 ml of ethanol. Therefore, the amount of added EC with respect to the weight of the synthesized indium oxide would be approx. 22 wt.%, 54 wt.%, 91 wt.% and 109 wt.%, respectively (i.e., 6 mg, 15 mg, 24 mg and 30 mg of EC with respect to 27.6 mg of In2O3 that can be formed from 60 mg of indium nitrate), when the decomposition and nominal weight loss of EC during the curing process at 275 °C is not considered. Furthermore, inks were also prepared with 10 wt.% of poly(4-vinylphenol) (PVP) and polyethylenimine (PEI) in the semiconductor ink (i.e., 6 mg of PVP and PEI in 60 mg of indium nitrate). All of these inks (pristine In2O3, [10 wt.%, 25 wt.%, 40 wt.%, 50 wt.%] EC, 10 wt.% PVP and 10 wt.% PEI) were stirred for about 1 h to obtain homogeneous printable inks/solution i.e., the composite semiconductor precursor solution. In some embodiments, post addition of the organic polymer, the composite semiconductor precursor solution is subjected to stirring for about 30 minutes to about 2 hours, or till a homogeneous solution is obtained. The mixing, in non-limiting embodiments of the present disclosure is performed by methods such as but not limited to mechanical mixing, ultrasonication and so on.

In an embodiment, the composite semiconductor precursor solution may be prepared by dissolving 0.1 M of indium (III) nitrate hydrate ([In(NO3)3.xH2O], 99.99 wt.%, trace metal basis, Sigma Aldrich CHEMIE GmbH) in ethanol. 60 mg of indium nitrate salt is dissolved in 2 ml of ethanol solvent followed by addition of 0.2 ml of ethylene glycol. The EG was added to adjust the viscosity of the ink and to obtain homogeneous and isotropic semiconductor film over large area. 10 wt.% of hydroxypropyl methylcellulose (HPMC) is added to the ink. The weight percentage of the added polymer was calculated with respect to the amount of indium nitrate salt that was taken. 10 wt.% corresponds to 6 mg of HPMC with respect to 60 mg of the indium nitrate in 2 ml of ethanol. Therefore, the amount of added HPMC with respect to the weight of the synthesized indium oxide would be approx. 22 wt.% (i.e., 6 mg of HPMC with respect to 27.6 mg of In2O3 that can be formed from 60 mg of indium nitrate), when the decomposition and nominal weight loss of HPMC during the curing process at 275 °C is not considered. 0.5 ml of De-Ionized water is then added to the ink to facilitate low temperature hydrolysis. The ink was stirred for about 1 h to obtain homogeneous printable inks/solution i.e., the composite semiconductor precursor solution. In some embodiments, post addition of the organic polymer, the composite semiconductor precursor solution is subjected to stirring for about 30 minutes to about 2 hours, or till a homogeneous solution is obtained. The mixing, in non-limiting embodiments of the present disclosure is performed by methods such as but not limited to mechanical mixing, ultrasonication and so on.

In an embodiment, the composite semiconductor precursor solution may be prepared by dissolving 10 wt.% (with respect to the weight of indium nitrate salt) of polyvinyl acetate (PVA) in 1 ml of ethanol at a temperature of 60 °C. After the dissolution of PVA in ethanol, 1 ml of De-Ionized water is added while continuously stirring at room temperature. 0.1 M of indium (III) nitrate hydrate ([In(NO3)3.xH2O], 99.99 wt.%, trace metal basis, Sigma Aldrich CHEMIE GmbH) (i.e., 60 mg of indium nitrate salt) is added to the ink. The weight percentage of the added polymer was calculated with respect to the amount of indium nitrate salt that was taken. 10 wt.% corresponds to 6 mg of PVA with respect to 60 mg of the indium nitrate in 1 ml of ethanol and 1 ml of De-ionized water solution. Therefore, the amount of added PVA with respect to the weight of the synthesized indium oxide would be approx. 22 wt.% (i.e., 6 mg of PVA with respect to 27.6 mg of In2O3 that can be formed from 60 mg of indium nitrate), when the decomposition and nominal weight loss of PVA during the curing process at 275 °C is not considered. The ink was stirred for about 1 h to obtain homogeneous printable inks/solution i.e., the composite semiconductor precursor solution. In some embodiments, post addition of the organic polymer, the composite semiconductor precursor solution is subjected to stirring for about 30 minutes to about 2 hours, or till a homogeneous solution is obtained. The mixing, in non-limiting embodiments of the present disclosure is performed by methods such as but not limited to mechanical mixing, ultrasonication and so on.

In some embodiments, the composite semiconductor precursor solution, obtained in the above-described method, is further subjected to filtration before application to any surface. In some embodiments, the filtration is performed through filters or membranes having pore size ranging from about 0.2 µm to about 5 µm.

Commercially available high-quality ITO coated float glass (180 nm, <10 Ω sheet resistance) and polyimide (Kapton E, thickness~ 50 µm) substrates were chosen as one rigid and one flexible substrate to realize the printed TFTs. In the case of the ITO coated glass, the passive electrodes (source, drain and gate contact) were lithographically structured to obtain a channel width (W) and length (L) of 60 µm and 30 µm, respectively, whereas, on polyimide substrates, the passive electrodes of chromium/gold (Cr/Au) were thermally evaporated, maintaining a channel width (W) and length (L) of 60 µm and 20 µm, respectively. The top-gate FET device fabrication involved a two-layer inkjet printing of the semiconductor ink at the channel region of the pre-patterned substrates (either the glass or the polyimide) using a Dimatix DMP 2831 inkjet printer. After printing, the semiconductor films were pre-heated on a hot plate at 100 °C for 10 minutes, followed by annealing at a temperature of 275 °C with a ramp rate of 2 °C/min and a holding time of 1 h. Next, 15 layers of the CSPE ink was printed covering the semiconductor film, while maintaining a platen temperature of 40 °C. Finally, the commercially available poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) ink (Sigma Aldrich Chemie GmbH) was printed on top of the electrolytic insulator. Finally, the substrate with array of printed TFTs was heated on a hot plate at 50 °C in an effort to remove the excess solvent from the PEDOT: PSS layer.
Consider an example where the semiconductor thin films have been prepared using indium nitrate as the metal oxide precursor and a chosen concentration of EC in an ethanol and de-ionized water-based ink formulation that has been inkjet-printed and annealed at 275 °C. Here, the EC concentration has primarily been defined based on wt.% of EC compared to the indium nitrate precursor. Figure 1 compares the X-ray diffraction (XRD) data of pristine In2O3 with the ones with 10-50 wt.% of EC in the composite semiconductor film. In addition, it also shows XRD data of 10 wt.% PVA and 10 wt.% HMPC based composite semiconductor film. Interestingly, the diffraction profile of the pristine In2O3 film is predominantly amorphous or only weakly crystalline upon annealing at 275 °C. However, the crystallinity improves progressively with the addition of EC and even the composite film with 50 wt.% of EC remains well-crystalline thereby denoting a limited intermixing and a nanoscale phase separation. Likewise, the transmission electron micrographs recorded on pristine and 25 wt.% EC films, printed and annealed on free-standing Si3N4 membranes, reveal predominantly amorphous and nanocrystalline nature, respectively. Figure 2a shows a pure In2O3 films and Figure 2b shows In2O3 films with 25 wt.% EC. Scale bar in the Figures 1c and 1d images show 500 nm. Each one of the samples has been annealed at 275 °C at a ramp rate of 2 °C/min and a holding time of 1 hr. The pristine indium oxide film appears spatially homogeneous and amorphous-like feature less. Whereas, increasing inhomogeneity and small voids may be due to partial decomposition of EC. This results from local phase separation that can be seen in films with increasing EC content.

Ethyl cellulose is a long-chain organic polymer or a type of cellulose ether. It is non-toxic, biocompatible, possesses high mechanical strength and is widely used as food additive, water repellent coating, non-polar emulsifier and in pharmaceutical industries as a binder/adhesive to facilitate controlled drug release. EC is chemically inert and reacts only very weakly. It is adhesive in nature and has been exploited in the present disclosure to serve as a reinforcing agent to provide excellent film quality, albeit local inhomogeneities, and ensured crack arrest during mechanical bending fatigue tests. Next, the thermal decomposition behaviour of EC includes that EC partially decomposes to aromatic species around temperatures of 250 °C. Whereas, at temperatures above 400 °C, volatilization and complete removal of EC has been observed.

In an embodiment, the solution processing technique to fabricate the composite semiconductor material based device from the composite semiconductor precursor solution can be chosen from solution-processing techniques such as spin coating, dip coating, spray coating and bar coating, or jetting-type printing techniques such as inkjet printing, screen printing, aerosol-jet printing, electrohydrodynamic jet printing, gravure printing, spin coating, spray coating, chemical bath deposition and/or replication-type printing techniques such as gravure, reverse gravure, flexography, offset, screen printing and dry transfer/contact printing.

In an embodiment, the solution-processed/ printed composite semiconductor precursor solution is converted to the composite semiconductor material by annealing at a pre-selected temperature which is sufficient to create the high mobility inorganic semiconductor phase but does not melt or fully decompose the one or more organic polymers.

In some embodiments, the pre-selected annealing temperature may be between 150 °C to 400 °C. Further, in an embodiment, the solution-processed/ printed composite semiconductor precursor solution is converted to the composite semiconductor material by photo-curing with a pre-selected incident energy dose which is sufficient to create the high mobility inorganic semiconductor phase but does not melt or fully decompose the organic polymer(s).

The characterization of semiconductor thin films have been followed by the fabrication of electrolyte gated TFTs on rigid ITO coated glass substrates. A Composite Solid Polymer Electrolyte (CSPE) is used as the gate insulator and the operation voltage has been limited to ≤ 2 V. A channel width (60 µm) to length (30 µm) ratio of 2 has been used for the electronic devices on glass substrates; nonetheless, On-currents >3.5 mA (at VDS= 2 V) could be recorded for the low temperature annealed TFTs. Figures 3a-3d demonstrates the representative transfer characteristics of pristine In2O3 TFT and 10 wt.%, 25 wt.% and 40 wt.% EC containing composite semiconductor based TFTs, respectively. Here, the On-currents (ID,ON) of the representative devices with pristine In2O3 and 10 wt.%, 25 wt.% and 40 wt.% EC based composite semiconductor TFTs measured at a VDS of 1.0 V are found to be 1.8 mA, 1.4 mA, 1.6 mA and 1.3 mA, respectively. The comparable On-currents indicate that even at the EC concentration as high as 40 wt.%, the percolating nanocrystal mediated indium oxide thin film is sufficiently homogeneous and continuous in two dimension to support such high current density values. Next, the averaged transistor performance parameters are shown in Figure 4. The recorded average width-normalized On-currents (ID,ON/W), average width-normalized transconductance (gm/W), average threshold voltage (VT) and average linear mobility (µlin) values have been summarized with respective variability in each case. Alongside pristine In2O3 TFTs and 10 wt.%, 25 wt.%, 40 wt.% and 50 wt.% EC based composite semiconductor TFTs, here, (Figures 3e-3h) 10 wt.% each of PVA, HPMC, PEI, and PVP based TFTs have also been fabricated and characterized, respectively.

The value of VT has been extracted by plotting the square root of ID versus VGS and taking a linear extrapolation until the x-intercept.

Here, the linear (μ_lin ) mobility values have been estimated using:

μ_lin=L/(W C_DL V_DS ) ((∂I_D)/(∂V_GS ))……… (1)

where,
L and W represent the transistor channel length and width,
CDL is the specific electric charge double layer capacitance (considered to be 10 µF/cm2),
VDS is the applied drain voltage (0.5 V has been considered for the calculation of µlin),
ID and VGS are the drain current and gate voltage in the linear regime.

Notably, the recorded current density, and transconductance values have been consistently high and within the same given range for pristine In2O3 and up to 40 wt.% EC based composite semiconductor TFTs. In contrast, the TFTs based on 10 wt.% PEI and 10 wt.% PVP show very low current density and device mobility values; these polymers t are known to intermix and disrupt the atomic arrangement in oxide lattice demonstrate weak performance, for the weight percentages in consideration.

The average current density of 40 wt.% EC based TFTs have been slightly lower than the average current density values recorded until 25 wt.% EC based TFTs as shown in Figure 4. Consequently, only pristine In2O3 and 25 wt.% EC based TFTs are fabricated on flexible polymer (like Kapton E, Dupont Inc.) substrate for further electrical and mechanical property comparisons.

Consider, the TFTs are inkjet-printed onto polyimide substrates with pre-structured, thermally evaporated Cr/Au passives having channel width (60 µm) to length (20 µm) ratio of 3. The devices have been placed at the central region of the polyimide strips (about 10 cm long), so that they are subjected to the complete strain cycle during each cycle of the bending fatigue test. The devices have been placed in a way that the drive current directions can be parallel or perpendicular to the direction of the strain during the cyclic bending tests. The transfer characteristics of a large set of TFTs fabricated from pristine In2O3 and 25 wt.% EC based semiconductor ink, are shown in Figures 5a-5d, demonstrating limited variability of printed TFTs on polymer substrate. In fact, the observed variability has always been lower for the devices with EC based composite semiconductor ink as shown in Figure 5c and 5d, indicating highly reproducible and homogeneous film formation with EC. Notably, a maximum On-current >3.85 mA (at VDS= 2 V) has been recorded for 25 wt.% EC composite semiconductor based TFTs.

Next, a series of bending tests have been performed to systematically investigate and compare the mechanical performance of the pristine In2O3-based and the 25 wt.% EC based composite semiconductor TFTs. FETs are subjected to bending fatigue test (tension) routine with different bending radii, infinity, 5 mm, 2.5 mm, and 1.5 mm (100 cycles at every bending radius), respectively; The bending fatigue test unit is equipped with a fixed and a movable plate, where the plate distance determines the bending radius and strain, and the frequency of cycles determine the strain rate. Here, the unit has been operated at 1 Hz, and the bending radii has been progressively reduced from 5 mm to 2.5 mm and then 1.5 mm. Figures 6a and 6b shows transfer curves for FETs with no EC, subjected to different bending radii. Figure 6c and 6d show transfer curves of FETs with 25 wt.% EC in the composite semiconductor precursor solution, subjected to different bending radii. Figure 6e illustrates change in linear mobility of FETs with the bending fatigue tests performed at different bending radii. In this case, the devices have been strained in the perpendicular direction of the current flow in the transistor channel. During the bending tests, FETs are subjected to bending fatigue test (tension) routine with different bending radii, infinity, 5 mm, 2.5 mm, and 1.5 mm (100 cycles at every bending radius), respectively. Here, TFTs are placed at the outer surface (convex side) of the polyimide strip, and therefore have been subjected to tensile stress.

Notably, the ON-current (ID,ON) of the TFT with no EC (Figures 6a-b) deteriorates substantially upon bending fatigue test, whereas the device made of composite semiconductor precursor ink (25 wt.% EC), shown in Figure 6c-d, demonstrates nominal decrease in ON-current. Unsurprisingly, the estimated linear mobility follows an identical trend with severe deterioration in this benchmark performance parameter for pristine In2O3 and a nominal compromise in performance in the case of 25 wt.% EC based composite semiconductor TFTs as shown in Figure 6e. In this case, the devices have been strained in the perpendicular direction of the current flow in the transistor channel.

Next, the strained Kapton strip has been subjected to microscopic investigations to correlate the electrical performance with bending strain related structural changes, if any. SEM micrographs have been taken on printed pristine In2O3 and 25 wt.% EC films that have been left uncovered following the semiconductor layers printing, i.e., without the printed CSPE insulator and top gate PEDOT:PSS layers, on the same strip that underwent the bending fatigue tests at different bending radii. Figure 7 shows the SEM images of pristine In2O3 and 25 wt.% EC based films before bending tests (as shown in Figures 7a and 7d) and after the bending tests (as shown in Figures 7b, 7c, 7e-7f) up to 100 cycles at 1.5 mm bending radius. The films of no EC and 25 wt.% EC are strained in anti-parallel direction as shown in Figures 7b and 7e. The films of no EC and 25 wt.% EC are strained in parallel direction of the current flow in the transistor channel as shown in Figures 7c and 7f. Scale bars in Figures 7a and 7d represent 2 µm, in Figures 7b and 7e represent 5 µm and in Figures 7c and 7f represent 10 µm. The arrows represent the strain direction.

The pristine In2O3 film, before bending, appears featureless and amorphous as shown in Figure 7a. Whereas the semiconductor films, other than the electrode area, develops severe cracks, with the bending fatigue tests, irrespective of the direction of the stress applied. In contrast, the 25 wt.% EC composite semiconductor film shows usual local phase separation related inhomogeneity as shown in Figure 7b. However, the films remain quite unaltered and completely homogeneous after the bending tests at minimum bending radius of 1.5 mm, so that it is found difficult to locate the position of the metal electrodes as shown in Figure 7e-7f. Here, the phase separation at nanoscale may have resulted some EC (or its decomposition product) rich region, which can essentially be responsible for the crack arrest. In addition, owing to its binder/adhesive nature, EC may also contribute to preventing film delamination, when the substrate and the film are under high tensile stress.

Embodiments of the present disclosure teaches addition of an organic polymer to the metal oxide, to gain the mechanical flexibility, without compromising on performance of the electronic device. The presence of the organic polymer arrests the cracks generated during any mechanical bending of the electronic device.

Embodiments of the present disclosure provisions to develop selective polymer based composite inorganic/organic solution.

Embodiments of the present disclosure provisions a new route to fabricate low-temperature solution processed organic/inorganic hybrid semiconductor FETs, while proving to be mechanically reliable and with best electrical performance. Hence, the one or more organic polymers may also be used for other binary and tertiary oxide systems to improve the mechanical reliability of their devices and extend their applicability in flexible electronic industry.

The illustrated operations of proposed methods are described in a certain order. In alternative embodiments, certain operations may be performed in a different order, modified, or removed. Moreover, steps may be added to the above-described logic and still conform to the described embodiments. Further, operations described herein may occur sequentially or certain operations may be processed in parallel. Yet further, operations may be performed by a single processing unit or by distributed processing units.

Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based here on. Accordingly, the disclosure of the embodiments of the invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

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