OPTICAL CONCENTRATORS FOR ORGANIC PHOTOACTIVE CELLS
BACKGROUND
The present invention relates, in general, to organic photoactive cells.
In the times of depleting conventional energy resources, silicon-based photoactive cells are seen as one of the alternate sources of energy. However, photoactive cells fail to compete with conventional energy sources in the free market, without government support, due to their higher costs to end users. Another alternative being explored in lab these days is organic photoactive cells, which have low raw material cost compared to silicon-based photoactive cells. However, organic photoactive cells have low efficiencies compared to silicon-based photoactive cells.
In light of the foregoing discussion, there is a need to increase efficiency of organic photoactive cells while keeping the cost down. In addition, the design of organic photoactive cells should be such that it should be suitable for mass manufacturing.
SUMMARY
An object of the present invention is to provide an organic photoactive cell (and a manufacturing method and system thereof) that is suitable for mass manufacturing.
Another object of the present invention is to provide an organic photoactive cell that has higher efficiency, compared to conventional organic photoactive cells.

Yet another object of the present invention is to provide an organic photoactive cell that has lower cost, and has ease of manufacturing, compared to conventional organic photoactive cells.
Embodiments of the present invention provide an organic photoactive cell. The organic photoactive cell includes a substrate that is capable of providing optical concentration. The substrate has a first side and a second side. The second side of the substrate has one or more formations, such that the formations and the substrate is a one-piece unitary structure. These formations enable concentration of electromagnetic radiation incident on the second side of the substrate, towards one or more predefined regions on the first side of the substrate. The area covered by the predefined regions is smaller than the area of the substrate.
In accordance with an embodiment of the present invention, the formations are substantially semi-cylindrical in shape. Accordingly, the predefined regions are substantially rectangular in shape. In accordance with another embodiment of the present invention, the formations are substantially hemispherical in shape. Accordingly, the predefined regions are substantially circular in shape.
The organic photoactive cell further includes a first electrode formed over the first side of the substrate, a hole-transport layer formed over the first electrode, a photoactive layer formed over the hole-transport layer, and a second electrode formed over the photoactive layer. The photoactive layer substantially overlaps with the predefined regions.
In accordance with an embodiment of the present invention, the first side of the substrate includes one or more grooves in which the first electrode, the hole-transport layer, the photoactive layer and the second electrode are formed.

In accordance with an embodiment of the present invention, tine grooves substantially overlap with the predefined regions on the substrate.
As the substrate itself acts as an optical concentrator, there is no need to use a separate optical concentrator. In addition, the substrate may be molded with the formations in a single step. This makes the organic photoactive cell suitable for mass manufacturing, and easy to manufacture.
Moreover, lesser amount of expensive materials is required to achieve higher outputs, due to the concentrating effect of the formations. Therefore, the organic photoactive cell has higher efficiency while keeping the cost down, compared to conventional organic photoactive cells.
BRIEF DESCRIPTION OF DRAWINGS
Embodiments of the present invention will hereinafter be described in conjunction with the appended drawings provided to illustrate and not to limit the scope of the claims, wherein like designations denote like elements, and in which:
FIGs. 1A and 1B depict a top view and a front view of an organic photoactive cell,
in accordance with an embodiment of the present invention;
FIGs. 2A and 28 depict a top view and a front view of an organic photoactive cell,
in accordance with another embodiment of the present invention;
FIG. 3 depicts various layers of an organic photoactive cell, in accordance with
an embodiment of the present invention;
FIG. 4 is a cross-sectional view illustrating how electromagnetic radiation is
concentrated over a region, in accordance with an embodiment of the present
invention;
FIG. 5 depicts a cross-sectional view of a substrate and an optical concentrator,
in accordance with an embodiment of the present invention;

FIG. 6 depicts a system for manufacturing an organic photoactive cell, in accordance with an embodiment of the present invention; and FIG. 7 depicts a method of manufacturing an organic photoactive cell, in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION
Various embodiments of the present invention provide an organic photoactive cell, and a method and system for manufacturing the organic photoactive cell. An organic photoactive cell is defined as a cell whose functioning is based on activation of electrons due to incident photons.
Referring now to figures, FIGs. 1A and 1B depict a top view and a front view of an organic photoactive cell 100, in accordance with an embodiment of the present invention. Organic photoactive cell 100 includes a substrate 102 capable of providing optical concentration. Substrate 102 has a first side 104 and a second side 106. Second side 106 of substrate 102 has one or more formations, shown as a formation 108a, a formation 108b and a formation 108c. Formation 108a, formation 108b and formation 108c are hereinafter collectively referred as formations 108. Formations 108 and substrate 102 is a one-piece unitary structure. Formations 108 are capable of acting as one or more optical concentrators.
Formations 108 enable concentration of electromagnetic radiation incident on second side 106 of substrate 102, towards one or more predefined regions, shown as a predefined region 110a, a predefined region 110b and a predefined region 110c, on first side 104 of substrate 102. Predefined region 110a, predefined region 110b and predefined region 110c are hereinafter collectively referred as predefined regions 110. The area covered by predefined regions 110 is smaller than the area of substrate 102.

With reference to FIGs. 1A and 1B, formations 108 are substantially semi-cylindrical in shape. Accordingly, predefined regions 110 are substantially rectangular in shape.
Various layers may be formed over predefined regions 110 to form organic photoactive cell 100. For example, these layers may include a first electrode (not shown in FIGS. 1A and IB) formed over first side 104 of substrate 102, a hole-transport layer (not shown in FIGs. 1A and IB) formed over the first electrode, a photoactive layer (not shown in FIGs. 1A and 1B) formed over the hole-transport layer, and a second electrode (not shown in FIGs. 1A and 1B) formed over the photoactive layer. In accordance with an embodiment of the present invention, the photoactive layer substantially overlaps with predefined regions 110. Details of the first electrode, the hole-transport layer, the photoactive layer, and the second electrode have been provided in conjunction with FIG. 3.
In accordance with an embodiment of the present invention, first side 104 of substrate 102 includes one or more grooves (not shown in FIGs. 1A and 1B) in which the first electrode, the hole-transport layer, the photoactive layer and the second electrode may be formed. In accordance with an embodiment of the present invention, the grooves substantially overlap with predefined regions 110 on substrate 102. Details of such grooves have been provided in conjunction with FIG. 5.
It is to be understood that the specific designation for organic photoactive cell 100 and its various components is for the convenience of the reader and is not to be construed as limiting organic photoactive cell 100 to a specific size, shape, type, or arrangement of its components.
FIGs. 2A and 2B depict a top view and a front view of an organic photoactive cell 200, in accordance with another embodiment of the present invention. Organic photoactive cell 200 includes a substrate 202 capable of

providing optical concentration. Substrate 202 has a first side 204 and a second side 206. Second side 206 of substrate 202 has one or more formations, shown as a formation 208a, a formation 208b and a formation 208c. Formation 208a, formation 208b and formation 208c are hereinafter collectively referred as formations 208. Formations 208 and substrate 202 is a one-piece unitary structure. Formations 208 are capable of acting as one or more optical concentrators.
Formations 208 enable concentration of electromagnetic radiation incident on second side 206 of substrate 202, towards one or more predefined regions, shown as a predefined region 210a, a predefined region 210b and a predefined region 210c, on first side 204 of substrate 202. Predefined region 210a, predefined region 210b and predefined region 210c are hereinafter collectively referred as predefined regions 210. The area covered by predefined regions 210 is smaller than the area of substrate 202.
With reference to FIGs. 2A and 2B, formations 208 are substantially hemispherical in shape. Accordingly, predefined regions 210 are substantially circular in shape.
Various layers may be formed over predefined regions 210 to form organic photoactive cell 200. For example, these layers may include a first electrode (not shown in FIGS. 2A and 2B) formed over first side 204 of substrate 202, a hole-transport layer (not shown in FIGs. 2A and 2B) formed over the first electrode, a photoactive layer (not shown in FIGs. 2A and 28) formed over the hole-transport layer, and a second electrode (not shown in FIGs. 2A and 2B) formed over the photoactive layer. In accordance with an embodiment of the present Invention, the photoactive layer substantially overlaps with predefined regions 210. Details of the first electrode, the hole-transport layer, the photoactive layer, and the second electrode have been provided in conjunction with FIG. 3.

In accordance with an embodiment of the present invention, first side 204 of substrate 202 includes one or more grooves (not shown in FIGs. 2A and 2B) in which the first electrode, the hole-transport layer, the photoactive layer and the second electrode may be formed. In accordance with an embodiment of the present invention, the grooves substantially overlap with predefined regions 210 on substrate 202. Details of such grooves have been provided in conjunction with FIG. 5.
It is to be understood that the specific designation for organic photoactive cell 200 and its various components is for the convenience of the reader and is not to be construed as limiting organic photoactive cell 200 to a specific size, shape, type, or arrangement of its components.
FIG. 3 depicts various layers of an organic photoactive cell, in accordance with an embodiment of the present invention. FIG. 3 shows a portion of a substrate 302 having a formation 304 on one side and a predefined region 306 on the other side. Formation 304 and substrate 302 is a one-piece unitary structure. The area covered by predefined region 306 is smaller than the area of substrate 302. In addition, the organic photoactive cell includes a first electrode 308, a hole-transport layer 310, a photoactive layer 312 and a second electrode 314.
Substrate 302 is optically transparent, that is, allows a large amount of electromagnetic radiation incident on its surface to pass through with minimal reflection from its surface. In one example, substrate 302 may be made of an optically-transparent material that is tolerant to moisture, Ultra-Violet (UV) radiation, abrasion, and natural temperature variations. The optically-transparent material may, for example, have an optical transparency greater than 85 %. Examples of such optically-transparent materials include, but are not limited to, glass, plastics, polycarbonates, polymers, and acrylics. The optically-transparent material may, for example, have a refractive index greater than 1.4.

In accordance with an embodiment of the present invention, substrate 302 may be coated with an anti-reflective coating to reduce loss of electromagnetic radiation incident on the organic photoactive cell. The anti-reflective coating minimizes reflection occurring at a medium boundary between air and substrate 302.
First electrode 308 is formed over predefined region 306 of substrate 302. A first conductive material is used to form first electrode 308. In accordance with an embodiment of the present invention, first electrode 308 is optically transparent. Accordingly, the first conductive material may, for example, be a transparent conductive oxide, such as Indium Tin Oxide (ITO), Zinc Oxide, Aluminum-doped Zinc Oxide, and Fluorine-doped Tin Oxide (FTO). Alternatively, a suitable transparent conductive polymer may be used as the first conductive material.
Hole-transport layer 310 is formed over first electrode 308. A hole-
transport material is used to form hole-transport layer 310 over first electrode 308.
Examples of the hole-transport material include, but are not limited to, Poly(3,4-
ethylenedioxythiophene) (PEDOT), Poly(3,4-ethylenedioxythiophene)
poly(styrenesulfonate)(PEDOT:PSS).
Hole-transport layer 310 allows incident electromagnetic radiation to pass through towards photoactive layer 312. In one example, hole-transport layer 310 may be made of a hole-transport material that is optically transparent in a specific region of the incident electromagnetic radiation, for example, the visible spectrum and/or Infra-Red (IR) radiation.
In accordance with an embodiment of the present invention, the thickness of hole-transport layer 310 is adjusted to allow proper transmission of incident electromagnetic radiation and transportation of charge carriers simultaneously.

For example, the thickness of hole-transport layer 310 may range from 30 nm to 150 nm.
Photoactive layer 312 is formed over hole-transport layer 310. A photoactive material is used to form photoactive layer 312 over hole-transport layer 310. In one example, the photoactive material may include an active polymer and a fullerene-based electron acceptor. An active polymer is an organic polymer that generates charge carriers upon being activated by incident electromagnetic radiation. In another example, the photoactive material may include a nano-particle-based electron acceptor, instead of a fullerene-based electron acceptor.
Second electrode 314 is formed over photoactive layer 312. A second conductive material is used to form second electrode 314 over photoactive layer 312. The second conductive material may, for example, be Aluminum, Silver, Calcium and Barium.
In accordance with an embodiment of the present invention, the organic photoactive cell further includes a covering member (not shown in FIG. 3) positioned over second electrode 314. The covering member protects first electrode 308, hole-transport layer 310, photoactive layer 312 and second electrode 314 from environmental damage. The covering member may, for example, be a plastic cover.
With reference to FIG. 3, an arrow 316 depicts the side from which electromagnetic radiation is incident on the organic photoactive cell. Electromagnetic radiation incident over the organic photoactive cell from this side is concentrated by formation 304 towards predefined region 306. Consequently, the electromagnetic radiation is incident on photoactive layer 312, and electron-hole pairs are created in photoactive layer 312. The electromagnetic radiation may, for example, include IR radiation, visible spectrum, and UV radiation.

Electrons and holes are separated at an interface between photoactive layer 312 and hole-transport layer 310, thereby generating a voltage. When a load is connected across first electrode 308 and second electrode 314, the generated voltage drives current, thereby producing electricity.
FIG. 4 is a cross-sectional view illustrating how electromagnetic radiation is concentrated over predefined region 306, in accordance with an embodiment of the present invention.
With reference to FIG. 4, a ray 402 is incident on formation 304 at a non¬zero angle of incidence. At the medium boundary between air and formation 304, ray 402 refracts with an angle of refraction smaller than its angle of incidence, and passes towards predefined region 306.
Similarly, a ray 404, a ray 408 and a ray 410 are incident on formation 304 at non-zero angles of incidence. Ray 404, ray 408 and ray 410 refract with angles of refraction smaller than their angle of incidence, and pass towards predefined region 306.
A ray 406 is incident on formation 304 at an angle of incidence equal to zero. Ray 406 passes through formation 304 without any refraction, towards predefined region 306.
Rays incident at different angles of incidence are concentrated towards predefined region 306. Consequently, these rays are incident on photoactive layer 312. In this way, formation 304 is capable of providing a concentration ratio between 5:1 and 1.5:1. The concentration ratio is a ratio of the area on which electromagnetic radiation is incident and the area on which the incident electromagnetic radiation is concentrated.

The concentration ratio may, for example, depend on various factors, such as shape and dimensions of formation 304. FIG. 5 depicts a cross-sectional view of substrate 302 and formation 304, in accordance with an embodiment of the present invention. With reference to FIG. 5, substrate 302 and formation 304 could include a rectangular portion and a semi-circular portion. The rectangular portion has a depth 'd', while the semi-circular portion has a radius 'r'. Different concentration ratios may be achieved by altering the depth 'd' and the radius 'r'. The depth 'd' may, for example, be greater than or equal to 1 mm, while the radius 'r' may, for example, be greater than or equal to 1 mm.
In an embodiment of the present invention, formation 304 is substantially semi-cylindrical in shape, and predefined region 306 is substantially rectangular in shape, as depicted in FlGs. 1A and 1B. In one example, the radius 'r' may be 3 mm and the depth 'd' may range from 2 mm to 3 mm. In such a case, formation 304 may provide a concentration ratio of 3:1. Accordingly, the width of predefined region 306 may range from 2 mm to 3 mm. In another example, the radius 'r' may be 2 mm and the depth 'd' may range from 2 mm to 3 mm. In such a case, formation 304 may provide a concentration ratio of 2:1. Accordingly, the width of predefined region 306 may range from 2 mm to 3 mm.
In an embodiment of the present invention, formation 304 is substantially hemispherical in shape, and predefined region 306 is substantially circular in shape, as depicted in FIGs. 2A and 2B. In one example, the radius 'r' may be 3 mm and the depth 'd' may range from 2 mm to 3 mm. In such a case, formation 304 may provide a concentration ratio of 3:1. Accordingly, the diameter of predefined region 306 may range from 2 mm to 3 mm. In another example, the radius 'r' may be 2 mm and the depth 'd' may range from 2 mm to 3 mm. In such a case, formation 304 may provide a concentration ratio of 2:1. Accordingly, the diameter of predefined region 306 may range from 2 mm to 3 mm.

As the number of photons impinging on photoactive layer 312 increases, the number of charge carriers also increases. This results in an increase in the efficiency of the organic photoactive cell.
In addition, the temperature of the organic photoactive cell increases, as concentration ratio increases. The increase in temperature assists proper diffusion of charge carriers, thereby increasing the probability of collection of the charge carriers. This further enhances the efficiency of the organic photoactive cell.
With reference to FIG. 5, substrate 302 includes one or more grooves, shown as a groove 502, substantially overlapping with predefined region 306. Groove 502 may, for example, be integrally attached or molded to substrate 302.
The shape and/or size of groove 502 may, for example, depend on the shape and/or size of formation 304. In one example, formation 304 may be substantially semi-cylindrical in shape. In such a case, groove 502 may be made substantially rectangular in shape. In another example, formation 304 may be substantially hemispherical in shape. In such a case, groove 502 may be made substantially circular in shape.
First electrode 308, hole-transport layer 310, photoactive layer 312 and second electrode 314 may be formed in groove 502. The covering member may then be positioned over groove 502, and sealed to provide a hermetic seal.
It is to be understood that the specific designation for the organic photoactive cell and its various components is for the convenience of the reader and is not to be construed as limiting the organic photoactive cell to a specific size, shape, type, or arrangement of its components.

In accordance with an alternative embodiment of the present invention, the covering member is capable of providing optical concentration. Accordingly, the covering member may be designed so as to provide the concentrating effect. In such a case, various layers of the organic photoactive cell, such as first electrode 308, hole-transport layer 310, photoactive layer 312 and second electrode 314 depicted in FIG. 3, are formed over a planar substrate. Subsequently, the covering member with in-built optical concentrators is positioned over the layers of the organic photoactive cell.
Accordingly, the covering member and second electrode 314 are made optically transparent, to allow electromagnetic radiation falling on the covering member to pass towards photoactive layer 312. In such a case, second electrode 314 may be made of a transparent conductive oxide, such as Indium Tin Oxide (ITO), Zinc Oxide, Aluminum-doped Zinc Oxide, and Fluorine-doped Tin Oxide (FTO). Alternatively, a suitable transparent conductive polymer may be used to form second electrode 314.
The covering member may be made of an optically-transparent material that is tolerant to moisture, UV radiation, abrasion, and natural temperature variations. The optically-transparent material may, for example, have an optical transparency greater than 85 %. Examples of such optically-transparent materials include, but are not limited to, glass, plastics, polycarbonates, polymers, and acrylics. The optically-transparent material may, for example, have a refractive index greater than 1.4.
The covering member may be designed in a manner similar to substrate 102 (depicted in FIG. 1) or substrate 202 (depicted in FIG. 2). The covering member has a first side and a second side, wherein the first side of the covering member is adjacent to second electrode 314. The second side of the covering member has one or more formations, such that the formations and the covering member is a one-piece unitary structure. These formations are capable of acting

as one or more optical concentrators. The formations enable concentration of electromagnetic radiation incident on the second side of the covering member, towards one or more predefined regions on the first side of the covering member. The area covered by the predefined regions is smaller than the area of the covering member. Accordingly, photoactive layer 312 is formed in a manner that photoactive layer 312 substantially overlaps with these predefined regions.
In accordance with a specific embodiment of the present invention, the substrate includes one or more grooves that substantially overlap with the predefined regions on the covering member. First electrode 308, hole-transport layer 310, photoactive layer 312 and second electrode 314 may be formed in these grooves.
In accordance with an embodiment of the present invention, the formations are substantially semi-cylindrical in shape. Accordingly, the predefined regions on the covering member may be substantially rectangular in shape. In accordance with another embodiment of the present invention, the formations are substantially hemispherical in shape. Accordingly, the predefined regions on the covering member may be substantially circular in shape.
FIG. 6 depicts a system 600 for manufacturing an organic photoactive cell, in accordance with an embodiment of the present invention. System 600 includes a substrate-obtaining unit 602, a first-electrode forming unit 604, a hole-transport-layer forming unit 606, a photoactive-layer forming unit 608, and a second-electrode forming unit 610.
Substrate-obtaining unit 602 obtains a substrate, as required. The substrate has a first side and a second side. The second side of the substrate has one or more formations, such that the formations and the substrate is a one-piece unitary structure.

In accordance with an embodiment of the present invention, the formations are integrally molded to the substrate. Accordingly, substrate-obtaining unit 602 may, for example, be an Injection molding machine that is configured to mold a polymeric material to form the substrate, such that the formations are formed during injection molding.
The substrate may, for example, be made of an optically-transparent material that is tolerant to moisture, UV radiation, abrasion, and natural temperature variations. For example, an optically-transparent material may be used in conjugation with certain UV-resistant materials. The optically-transparent material may, for example, have an optical transparency greater than 85 %. Examples of such optically-transparent materials include, but are not limited to, glass, plastics, polycarbonates, polymers, and acrylics. The optically-transparent material may, for example, have a refractive index greater than 1.4.
As described earlier, the formations enable concentration of electromagnetic radiation incident on the second side of the substrate, towards one or more predefined regions on the first side of the substrate. Accordingly, substrate-obtaining unit 602 may form one or more grooves substantially overlapping with these predefined regions.
First-electrode forming unit 604 then forms a first electrode over the first side of the substrate. First-electrode forming unit 604 may, for example, deposit a first conductive material over the first side of the substrate. The first conductive material may, for example, be a transparent conductive oxide, such as Indium Tin Oxide (ITO), Zinc Oxide, Aluminum-doped Zinc Oxide, and Fluorine-doped Tin Oxide (FTO). Alternatively, a suitable transparent conductive polymer may be used as the first conductive material.
Subsequently, hole-transport-layer forming unit 606 forms a hole-transport layer over the first electrode. Hole-transport-layer forming unit 606 may, for

example, coat a hole-transport material over the first electrode. Examples of the hole-transport material include, but are not limited to. Poly (3,4-ethylenedioxythiophene) (PEDOT), Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)(PEDOT:PSS).
Thereafter, photoactive-layer forming unit 608 forms a photoactive layer over the hole-transport layer. Photoactive-layer forming unit 608 may, for example, coat a photoactive material over the hole-transport layer. In one example, the photoactive material may include an active polymer and a fullerene-based electron acceptor. In another example, the photoactive material may include a nano-particle-based electron acceptor, instead of a fullerene-based electron acceptor.
In accordance with an embodiment of the present invention, photoactive-layer forming unit 608 forms the photoactive layer in a manner that the photoactive layer substantially overlaps with the predefined regions.
Second-electrode forming unit 610 then forms a second electrode over the photoactive layer. Second-electrode forming unit 610 may, for example, deposit a second conductive material over the photoactive layer. The second conductive material may, for example, be Aluminum, Silver, Calcium and Barium.
In accordance with a specific embodiment of the present invention, the first electrode, the hole-transport layer, the photoactive layer and the second electrode may be formed in the grooves.
In accordance with an additional embodiment of the present invention, system 600 also includes a positioning unit for positioning a covering member over the grooves, and a sealing unit for sealing the covering member with the substrate.

FIG. 6 is merely an example, which should not unduly limit the scope of the claims herein.
FIG. 7 depicts a method of manufacturing an organic photoactive cell, in accordance with an embodiment of the present invention.
At step 702, a substrate is obtained. The substrate has a first side and a second side. The second side of the substrate has one or more formations, such that the formations and the substrate is a one-piece unitary structure.
In accordance with an embodiment of the present invention, the formations are integrally molded to the substrate. Accordingly, step 702 may, for example, be performed by an injection molding machine that is configured to mold a polymeric material to form the substrate, such that the formations are formed during injection molding.
The substrate may, for example, be made of an optically-transparent material that is tolerant to moisture, UV radiation, abrasion, and natural temperature variations. For example, an optically-transparent material may be used in conjugation with certain UV-resistant materials. The optically-transparent material may, for example, have an optical transparency greater than 85 %. Examples of such optically-transparent materials include, but are not limited to, glass, plastics, polycarbonates, polymers, and acrylics. The optically-transparent material may, for example, have a refractive index greater than 1.4.
As described earlier, the formations enable concentration of electromagnetic radiation incident on the second side of the substrate, towards one or more predefined regions on the first side of the substrate. Accordingly, step 702 may include forming one or more grooves substantially overlapping with these predefined regions.

At step 704, a first electrode is formed over the first side of the substrate. Step 704 may, for example, include depositing a first conductive material over the first side of the substrate. The first conductive material may, for example, be a transparent conductive oxide, such as Indium Tin Oxide (ITO), Zinc Oxide, Aluminum-doped Zinc Oxide, and Fluorine-doped Tin Oxide (FTO). Alternatively, a suitable transparent conductive polymer may be used as the first conductive material.
Subsequently, at step 706, a hole-transport layer is formed over the first electrode. Step 706 may, for example, include coating a hole-transport material over the first electrode. Examples of the hole-transport material include, but are not limited to. Poly (3,4-ethylenedioxythiophene) (PEDOT), Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOTPSS).
Thereafter, at step 708, a photoactive layer is formed over the hole-transport layer. Step 708 may, for example, include coating a photoactive material over the hole-transport layer. In one example, the photoactive material may include an active polymer and a fullerene-based electron acceptor. In another example, the photoactive material may include a nano-particle-based electron acceptor, instead of a fullerene-based electron acceptor.
In accordance with an embodiment of the present invention, the photoactive layer is formed in a manner that the photoactive layer substantially overlaps with the predefined regions.
At step 710, a second electrode is formed over the photoactive layer. Step 710 may, for example, include depositing a second conductive material over the photoactive layer. The second conductive material may, for example, be Aluminum, Silver, Calcium and Barium.

In accordance with a specific embodiment of the present invention, the first electrode, the hole-transport layer, the photoactive layer and the second electrode may be formed in the grooves.
In accordance with an additional embodiment of the present invention, a step of positioning a covering member over the grooves, and a step of sealing the covering member with the substrate may be performed.
It should be noted here that steps 702-710 are only illustrative and other alternatives can also be provided where steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.
In accordance with a specific embodiment of the present invention, a plurality of organic photoactive cells could be connected with each other to form a photoactive module. The photoactive module can be used in various applications. For example, an array of photoactive modules may be used to generate electricity on a large scale for grid power supply. In another example, photoactive modules may be used to generate electricity on a small scale for home/office use. Alternatively, photoactive modules may be used to generate electricity for stand-alone electrical devices, such as automobiles and spacecraft.
Embodiments of the present invention provide an organic photoactive cell that incorporates a substrate with in-built optical concentrators. As the substrate itself acts as an optical concentrator, there is no need to use a separate optical concentrator. In addition, the substrate may be molded with the optical concentrators in a single step. This makes the organic photoactive cell suitable for mass manufacturing, and easy to manufacture.

Moreover, lesser amount of expensive materials is required to achieve higher outputs, due to the concentrating effect of the optical concentrators. Therefore, the organic photoactive cell has lower cost and higher efficiency.
In the description herein for the embodiments of the present invention, numerous specific details are provided, such as examples of components and/or methods, to provide a thorough understanding of the embodiments of the present invention. One skilled in the relevant art will recognize, however, that an embodiment of the present invention can be practiced without one or more of the specific details, or with other apparatus, systems, assemblies, methods, components, materials, parts, and/or the like. In other instances, well-known structures, materials, or operations are not specifically shown or described in detail to avoid obscuring aspects of the embodiments of the present invention.
Reference throughout this specification to "one embodiment", "an embodiment", or "a specific embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of an embodiment of the present invention and not necessarily in all embodiments. Thus, respective appearances of the phrases "in one embodiment", "in an embodiment", or "in a specific embodiment" in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any specific embodiment of the present invention may be combined in any suitable manner with one or more other embodiments. It is to be understood that other variations and modifications of the embodiments of the present invention described and illustrated herein are possible in light of the teachings herein and are to be considered as part of the spirit and scope of the present invention.
It will also be appreciated that one or more of the elements depicted in the drawings/figures can also be implemented in a more separated or integrated

manner, or even removed or rendered as inoperable in certain cases, as is useful in accordance with a particular application.
As used in the description herein and throughout the claims that follow, "a", "an", and "the" includes plural references unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the meaning of "in" includes "in" and "on" unless the context clearly dictates otherwise.
The foregoing description of illustrated embodiments of the present invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the present invention to the precise forms disclosed herein. While specific embodiments of, and examples for, the present invention are described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of the present invention, as those skilled in the relevant art will recognize and appreciate. As indicated, these modifications may be made to the present invention in light of the foregoing description of illustrated embodiments of the present invention and are to be included within the spirit and scope of the present invention.
Thus, while the present invention has been described herein with reference to particular embodiments thereof, a latitude of modification, various changes and substitutions are intended in the foregoing disclosures, and it will be appreciated that in some instances some features of the embodiments of the present invention will be employed without a corresponding use of other features without departing from the scope and spirit of the present invention as set forth. Therefore, many modifications may be made to adapt a particular situation or material to the essential scope and spirit of the present invention. It is intended that the present invention not be limited to the particular terms used in following claims and/or to the particular embodiment disclosed as the best mode contemplated for carrying out this present invention, but that the present invention will include any and all embodiments and equivalents falling within the scope of the appended claims.

CLAIMS WHAT IS CLAIMED IS:
1. An organic photoactive cell comprising:
a substrate capable of providing optical concentration, the substrate having a first side and a second side, the second side of the substrate having one or more formations, such that the one or more formations and the substrate is a one-piece unitary structure, one or more formations enabling concentration of electromagnetic radiation incident on the second side of the substrate, towards one or more predefined regions on the first side of the substrate, the area covered by the one or more predefined regions being smaller than the area of the substrate;
a first electrode formed over the first side of the substrate, the first electrode being optically transparent;
a hole-transport layer formed over the first electrode;
a photoactive layer formed over the hole-transport layer, wherein the photoactive layer substantially overlaps with the one or more predefined regions; and
a second electrode formed over the photoactive layer.
2. The organic photoactive cell of claim 1, wherein the one or more formations are substantially semi-cylindrical in shape and the one or more predefined regions are substantially rectangular in shape.
3. The organic photoactive cell of claim 1, wherein the one or more formations are substantially hemispherical in shape and the one or more predefined regions are substantially circular in shape.

4. The organic photoactive cell of claim 1, wherein the first side of the substrate connprises one or more grooves in which the first electrode, the hole-transport layer, the photoactive layer and the second electrode are formed.
5. The organic photoactive cell of claim 4, wherein the one or more grooves substantially overlap with the one or more predefined regions on the substrate.
6. An organic photoactive cell comprising:
a substrate;
a first electrode formed over the substrate;
a hole-transport layer formed over the first electrode;
a photoactive layer formed over the hole-transport layer;
a second electrode formed over the photoactive layer, the second electrode being optically transparent; and
a covering member positioned over the second electrode, the covering member being capable of providing optical concentration, the covering member having a first side and a second side, the first side of the covering member being adjacent to the second electrode, the second side of the covering member having one or more formations, such that the one or more formations and the covering member is a one-piece unitary structure, the one or more formations enabling concentration of electromagnetic radiation incident on the second side of the covering member, towards one or more predefined regions on the first side of the covering member, the area covered by the one or more predefined regions being smaller than the area of the covering member,
wherein the photoactive layer substantially overlaps with the one or more predefined regions on the covering member.
7. The organic photoactive cell of claim 6, wherein the one or more formations
are substantially semi-cylindrical in shape and the one or more predefined
regions are substantially rectangular in shape.

8. The organic photoactive cell of claim 6, wherein the one or more formations
are substantially hemispherical in shape and the one or more predefined
regions are substantially circular in shape.
9. The organic photoactive cell of claim 6, wherein the substrate comprises one
or more grooves in which the first electrode, the hole-transport layer, the
photoactive layer and the second electrode are formed, and wherein the one
or more grooves substantially overlap with the one or more predefined
regions on the covering member.
10. An organic photoactive cell substantially as herein above described in the
specification with reference to the accompanying drawings.