A PROCESS OF FORMING AN ELECTRODE INTERCONNECTION IN AN INTEGRATED MULTILAYER THIN-FILM ELECTRONIC DEVICE

Abstract

A process of forming an electrode interconnection between at least two adjacent unit devices in an integrated multilayer thin-film electronic device comprising: providing an intermediary device that comprises: a first electrode layer on a thin film substrate comprising a first patterned coating that includes at least two spaced apart first electrode sections of adjacent unit devices; a first functional layer comprising a substantially continuous coating over the first electrode layer; and a second functional layer comprising a second patterned coating on the first functional layer comprising at least two spaced apart functional sections, each functional section positioned on the first functional layer to overlay a portion of one of the first electrode sections so to define a gap portion between adjacent functional sections that includes a portion of that first electrode section and the first functional layer; and applying a second electrode layer over the second functional layer as a third patterned coating that includes at least two spaced apart second electrode sections of adjacent unit devices, each second electrode section being positioned to overlay at least one functional section of the second functional layer and a portion of an adjoining gap portion that includes at least one portion of the first electrode section of an adjacent unit device, the third patterned coating being formed using a solution including a conductive species and at least a first solvent, wherein the first functional layer is soluble in the first solvent and the second functional layer has a low to zero solubility in the first solvent, such that application of the second electrode layer to the gap portion forms at least one electrically conductive path through the first functional layer between the first electrode and the second electrode of adjacent unit devices.

Claims

1. A process of forming an electrode interconnection between at least two adjacent unit devices in an integrated multilayer thin-film electronic device comprising: providing an intermediary device that comprises: a first electrode layer on a thin film substrate comprising a first patterned coating that includes at least two spaced apart first electrode sections of adjacent unit devices; a first functional layer comprising a substantially continuous coating over the first electrode layer; and a second functional layer comprising a second patterned coating on the first functional layer comprising at least two spaced apart functional sections, each functional section positioned on the first functional layer to overlay a portion of one of the first electrode sections so to define a gap portion between adjacent functional sections that includes a portion of that first electrode section and the first functional layer; and applying a second electrode layer over the second functional layer as a third patterned coating that includes at least two spaced apart second electrode sections of adjacent unit devices, each second electrode section being positioned to overlay at least one functional section of the second functional layer and a portion of an adjoining gap portion that includes at least one portion of the first electrode section of an adjacent unit device, the third patterned coating being formed using a solution including a conductive species and at least a first solvent, wherein the first functional layer is soluble in the first solvent and the second functional layer has a low to zero solubility in the first solvent, such that application of the second electrode layer to the gap portion forms at least one electrically conductive path through the first functional layer between the first electrode and the second electrode of adjacent unit devices.

2. The process according to claim 1, wherein the second functional layer has a substantially low to zero solubility in the first solvent.

3. The process according to claim 1, wherein the first functional layer comprises a polar layer and the second functional layer comprise a non-polar layer; or the first functional layer comprises a non-polar layer and the second functional layer comprises a polar layer and wherein the first solvent has the same polarity as the first functional layer.

4. (canceled)

5. The process according to claim 1, wherein the first solvent comprises: DMF, DMSO, Y-butyrolactone, acetone, acetyl acetone, ethyl acetoacetate, NMP, DMAC, THF or combinations thereof; isopropanol, n-butanol, isobutanol, ethanol, methanol, acetic acid, ethylene glycol, propylene glycol, glycerol, allyl alcohol, propargyl alcohol, inositol or combinations thereof; or benzene, toluene, xylenes, trimethylbenzene, chlorobenzene, dichlorobenzene, chloroform, dichloromethane, anisole, propylene glycol methyl ether acetate, diethylene glycol mono butyl ether, di(propylene glycol) dimethyl ether or combinations thereof.

6. (canceled)

7. The process according to claim 1, wherein the at least one electrically conductive path between the first electrode and the second electrode of adjacent unit devices comprises one or more micro- to nano-sized paths, preferably one or more micro- to nano-sized channels through the first functional layer, and wherein the at least one electrically conductive path between the first electrode layer and second electrode layer preferably comprises one or more defects in the first functional layer, preferably one or more pinhole defects through the thickness of the first functional layer, wherein preferably substantially all, or all of the gap portion provides the conductive path between the first electrode and the second electrode.

8-9. (canceled)

10. The process according to claim 1, wherein the intermediary device includes at least one of: at least one further functional layer between the first and second functional layers; or at least one further functional layer between the first electrode layer and the first functional layer, and preferably wherein each further functional layer comprising patterned coating that includes at least two spaced apart second sections having a complementary configuration to the functional sections of the second functional layer.

11. (canceled)

12. The process according to claim 1, wherein the intermediary device includes at least one further functional layer between the substrate and the first functional layer.

13. The process according to claim 1, wherein further comprising forming an intermediary device by: applying a first electrode layer on a thin film substrate comprising a first patterned coating that includes at least two spaced apart first electrode sections of adjacent unit devices; applying a first functional layer comprising a substantially continuous coating over the first electrode layer; and applying a second functional layer comprising a second patterned coating on the first functional layer comprising at least two spaced apart functional sections, each functional section positioned on the first functional layer to overlay a portion of one of the first electrode sections so to define a gap portion between adjacent functional sections that includes a portion of that first electrode section and the first functional layer.

14. (canceled)

15. The process according to claim 1, wherein the first patterned coating comprises a plurality of spaced apart discrete first electrode sections, each electrode section comprising a geometric shape arranged in a regular pattern on the thin-film substrate, and wherein each electrode section preferably has the same shape.

16-17. (canceled)

18. The process according to claim 1, wherein the second patterned coating comprises a complimentary pattern to the first patterned coating.

19. The process according to claim 1, wherein the gap portions between adjacent functional sections comprise the first electrode layer and first functional layer only.

20. The process according to claim 1, wherein the first patterned coating and second patterned coating comprise a plurality of spaced apart rectangular sections having a first longitudinal axis applied to a flexible strip having a second longitudinal axis aligned along the strip length, the rectangular sections being arranged on the flexible strip with the first longitudinal axis perpendicularly aligned to the second longitudinal axis.

21. The process according to claim 1, wherein the third patterned coating comprises: a complimentary pattern to the second patterned coating, and preferably the first patterned coating; or a grid, preferably a grid formed from a regular repeating geometric shape, the grid being preferably formed from a series of spaced apart elements, preferably a plurality of spaced apart lines, the thickness of selected portions of elements in the grid are preferably thickener relative to the thickness of adjoining elements in the grid to produce the configuration of a selected indicia within the thicker elements of the grid.

22-26. (canceled)

27. The process according to claim 21, wherein the colour of the second electrode layer is selected to contrast with the first functional layer and second functional layer, preferably to produce high-contrast lines relative to the colour of the first functional layer and second functional layer.

28. The process according to claim 1, wherein the thin-film substrate comprises a flexible substrate, or comprises at least one of a polymer, metal, ceramic or glass, preferably a polymer film.

29-31. (canceled)

32. The process according to claim 1, wherein the first functional layer comprises a photoactive layer, and the photoactive layer preferably comprises at least one of one or more organic photovoltaic compounds, or one or more perovskite photo-active compounds.

33. (canceled)

34. The process according to claim 32, wherein the second functional layer comprises a charge selective layer, the second electrode layer comprises a metallic electrode, preferably a silver electrode formed using a solution including the metal or ionic form of the metal and at least the first solvent, and the first electrode layer preferably comprises a transparent electrode layer.

35-36. (canceled)

37. The process according to claim 34, wherein the substrate includes one or more layers or coatings selected from at least one of: at least one coating of a transparent conductor layer; at least one hole transporting layer comprising an organic or inorganic semiconductor; or at least one electron transporting layer comprising an organic or inorganic conductor.

38. (canceled)

39. An integrated multilayer thin-film electronic device comprising: a first electrode layer on a thin film substrate comprising a first patterned coating that includes at least two spaced apart first electrode sections of adjacent unit devices; a first functional layer comprising a substantially continuous coating over the first electrode layer; and a second functional layer comprising a second patterned coating on the first functional layer comprising at least two spaced apart functional sections, each functional section positioned on the first functional layer to overlay a portion of one of the first electrode sections so to define a gap portion between adjacent functional sections that includes a portion of that first electrode section and the first functional layer; and a second electrode layer on the second functional layer comprising a third patterned coating that includes at least two spaced apart second electrode sections of adjacent unit devices, each second electrode section being positioned to overlay at least one functional section of the second functional layer and a portion of an adjoining gap portion that includes at least one portion of the first electrode section of an adjacent unit device, wherein each gap portion includes at least one electrically conductive path through the first functional layer between the first electrode and the second electrode of adjacent unit devices.

40. The device according to claim 39, wherein the at least one electrically conductive path between the first electrode and the second electrode comprises one or more micro- to nano-sized paths, preferably one or more micro- to nano-sized channel through the first functional layer, and wherein substantially all or all of the gap portion provides the conductive path between the first electrode and the second electrode.

41-68. (canceled)

Description

BRIEF DESCRIPTION OF THE FIGURES

[0119] The present invention will now be described with reference to the figures of the accompanying drawings, which illustrate particular preferred embodiments of the present invention, wherein:

[0120] FIG. 1 provides a schematic showing a comparison of three prior art approaches to forming an electrode interconnection in an integrated multilayer thin-film electronic device.

[0121] FIG. 2 illustrates the layers comprising a solar cell configured according to the present invention in (a) a conventional solar cell structure; (b) an inverted solar cell structure; and (b) a tandem solar cell structure.

[0122] FIG. 3 provides a schematic drawing of series-connected photovoltaic (PV) modules showing: (a) conventional module via patterned photo-active layers. (b) module design developed in this invention. An unpatterned photo-active layer is used and inter connections are formed via self-generated electrical paths.

[0123] FIG. 4 illustrates example designs of PV modules processed by roll-to-roll production that could be produced using the process of the present invention, including (a) Infinity PV module, (b) CSIRO's smart module and (c) CSIRO's perpendicular-module design.

[0124] FIG. 5 provides further examples of designs of PV modules that can be produced using the process of the present invention including: (a) the perpendicular-module and (b) a conventional parallel-module (c) un-conventional module design fabricated by using laser scribing (Belectric, Germany).

[0125] FIG. 6 illustrates various back electrode patterns for the device of the present invention showing: (a)(i) an example of mask design used for printing electrodes with homogenous lines; (a)(ii) a mask design used for printing electrodes with a grid pattern; (b) and (c) printing electrodes with a grid pattern incorporating variations in line thickness to provide a visual pattern.

[0126] FIG. 7 provides an example current density (per cell area rather than the whole module area for comparison)-voltage characteristics of a single PV cell and a perpendicular-module with 19 cells in series connection having device configuration: flexible ITO (transparent electrode)/PEIE (electron selective layer)/PI-4 (commercial photoactive ink)/S315 (hole selective layercommercial PEDOT:PSS ink)/PV-416 (back electrodecommercial silver paste).

DETAILED DESCRIPTION

[0127] The present invention describes a new way of forming electrical interconnections between two spaced apart electrodes in an integrated multilayer thin-film electronic device without having to include physical gaps in the patterning in the individual layers of that device.

Multilayer Thin-Film Electronic Device

[0128] The present invention relates to integrated multilayer thin-film electronic device and can be used for any solution-processed electronic devices such as organic transistors, OLEDs, organic memories and printed sensors. The present invention finds particular application with photovoltaic and optoelectronic solar devices such as include Organic solar cells, OPV, perovskite solar cells, roll-to-roll and will therefore be described in the context of those types of devices. However, it should be appreciated that the present invention can also relate to other solution-processed electronic device such as photoactive sensors, organic transistors, light emitting devices such as OLEDs, organic memories and printed sensors.

[0129] Photovoltaic cells, particularly thin film and flexible solar cells are formed as a multilayer coating on a substrate. FIGS. 2(a) and 2(b) illustrate examples of layer structure of the multilayer organic solar cell configured according to an embodiment of the present invention. As shown in FIGS. 2(a) and 2(b), this multilayer coating structure can be arranged on the substrate in at least two different arrangements termed in the art as (A) a conventional structure 50, or (B) as an inverted structure 60 (FIG. 2(b)). The nature and order of the transporting layersas well as the nature of the metal electrodedepends on whether the cell follows a regular or an inverted device architecture.

[0130] FIG. 2(a) represents a conventional structure 50 that is formed on a substrate having the following layers successively layered on a surface thereof: a transparent conductor (such as a transparent conductive oxide (TCO), conducting polymer or thin metal) with or without conducting grids, followed by a hole transporting layer; followed by the photoactive layer; followed by an electron transporting layer, and followed by a conductor layer (typically a metal).

[0131] FIG. 2(b) represents an inverted structure 60 that is formed on a substrate having the following layers successively layered on a surface thereof: a transparent conductor (such as a transparent conductive oxide (TCO), conducting polymer or thin metal) with or without conducting grids, followed by an electron transporting layer; followed by the photoactive layer; followed by a hole transporting layer, and followed by a conductor layer (typically a metal).

[0132] In an inverted structure 60, the electric charges exit the device in the opposite direction as in a normal device because the positive and negative electrodes are reversed. Inverted cells can utilize cathodes out of a more suitable material; inverted OPVs enjoy longer lifetimes than regularly structured OPVs, and they usually show higher efficiencies compared with the conventional counterparts.

[0133] It should be appreciated that the hole transporting layer or electron transporting layers could be omitted in some embodiments of the above conventional 50 and inverted 60 structures. These layers can therefore be optional in certain embodiments.

[0134] The solar cell may also comprise a tandem or multijunction solar cell 70. As shown in FIG. 2(c), a tandem structure is formed on a substrate using two stacked solar cell structures, i.e. a top cell and a bottom cell of the conventional or inverted structure. The stacked structure includes two different solar cells of the same or different configurations. The example provided comprises the following layers successively layered thereon: Transparent conductor layer (TCO, conducting polymer or thin metal) with or without collecting grids; followed by a Top cella solar cell either type A (FIG. 1A) or type B (FIG. 2B); followed by a Transparent conductor layer (TCO, conducting polymer or thin metal) with or without conducting grids; followed by a Bottom cell (a solar cell either type A (FIG. 2A) or type B (FIG. 2B); followed by a Metal (or conductor) layer. A substrate such as glass, plastic, metal or ceramic could also be used but should be understood to be optional.

[0135] Each layer can be formed by one of a number of coating techniques known in the art including casting, doctor blading, screen printing, inkjet printing, pad printing, knife coating, meniscus coating, slot die coating, gravure coating, reverse gravure coating, kiss coating, micro-roll coating, curtain coating, slide coating, spray coating, flexographic printing, offset printing, rotatory screen printing, or dip coating. It should be appreciated that a person skilled in the art would be able to adopt a suitable technique to apply each layer based on techniques known in the art.

[0136] The various layers can comprise a number of suitable components currently known in the art. Examples include: [0137] Suitable photoactive layers can be selected from one or more organic photovoltaic compounds, or one or more perovskite photo-active compounds. [0138] Suitable transparent conductor layer can be selected from transparent conductive oxides (TCO) include tin doped indium oxide (ITO), fluoride-doped tin oxide (FTO), doped zinc oxide such as aluminium doped zinc oxide (AZO), or indium doped cadmium-oxide; multi-layer hybrid film (TCO-metal-TCO for example); polymer-based conductors includes poly(3,4-ethylenedioxythiophene and polystyrene sulfonate mixture (PEDOT:PSS) with and without metal grids; [0139] Suitable hole transporting layers include a transparent conducting polymer such as at least one of Poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxythiophene and polystyrene sulfonate mixture (PEDOT:PSS), poly(4,4-dioctylcyclopentadithiophene); doped P3HT (Poly(3-hexylthiophene-2,5-diyl)) or the like; [0140] Suitable electron transporting layers include zinc oxide, titanium dioxide, tungsten trioxide, Polyethylenimine ethoxylated (PEIE) or the like; [0141] Suitable conductor layers comprise aluminium, silver, magnesium, copper, gold, or suitable alloys thereof or the like; and [0142] Suitable substrates include metals, polymers, ceramics, or glasses.

[0143] It should be appreciated that typically electron transporting layers are hole blocking layers or vice versa. Similarly, typically electron blocking layers are hole transporting layers or vice versa. Vacuum-based OLEDs tend to use additional layers (injecting layer, blocking layer) to push the efficiency further. Solution processed devices typically do not use such additional layers.

[0144] The photoactive layer can comprise one or more organic photoactive compounds in some embodiments. Preferably, the organic photoactive compounds are in the form of an ink. Organic photoactive layer generally comprises a combination of an electron donor material and an electron acceptor material. In some embodiments, the organic photoactive compounds comprise an organic photoactive layer composite ink comprising at least one electron donor material, at least one electron acceptor material, and an organic solvent. Other components may also be present to enhance the functionality of the photoactive layer, for example as taught in United States patent publication No. US20190393423A1 which teaches an organic photoactive layer comprising an electron donor material, an electron acceptor material, an organic solvent and an organic amine compound, the contents of which should be understood to be incorporated into this specification by this reference.

[0145] The electron donor material refers to a semiconductor material whose molecule can give electrons in an organic solar cell photoactive layer under the condition of light excitation so as to achieve charge separation. In some embodiments, the electron donor material comprises a conjugated polymer electron donor material and/or a conjugated small organic molecule electron donor material.

[0146] In embodiments, the conjugated polymer electron donor material comprises any one or a combination of two or more of P3HT (poly(3-hexylthiophene)), PTB7, PTB7-Th, PffBT4T-2OD and structure variants thereof, but is not limited thereto. The conjugated small organic molecule electron donor material preferably comprises a macromolecule based on benzodithiophene (BDT) as a core and a macromolecule based on oligothiophene as a core. For example, the conjugated small organic molecule electron donor material comprises DR3TSBDT, DRCN7T and structure variants thereof.

[0147] The electron acceptor material refers to a semiconductor material whose molecule can receive electrons in an organic solar cell photoactive layer under the condition of light excitation so as to achieve charge separation. In some embodiments, the electron acceptor material comprises any one or a combination of two or more of a fullerene electron acceptor material, a fullerene derivative electron acceptor material and a non-fullerene electron acceptor material, but is not limited thereto.

[0148] In embodiments, the fullerene electron acceptor material and the fullerene derivative electron acceptor material comprise any one or a combination of two or more of PCBM such as [6,6]-phenyl-C61-methyl butyrate (PC61BM) or PC71BM, Bis-PC61 BM and IC61BA, but is not limited thereto. The non-fullerene electron acceptor material preferably comprises an organic conjugated electron acceptor material. More preferably, the organic conjugated electron acceptor material comprises any one or a combination of two or more of a perylene diimide (PDI) derivative, a naphthdiimide (NDI) derivative, an indacene derivative, a fluorene derivative, a benzothiadiazole (BT) derivative and a subphthalocyanine (SubPc) derivative, but is not limited thereto.

[0149] The organic solvent preferably includes, but is not limited to, o-dichlorobenzene, chlorobenzene, chloroform, toluene, xylene, trimethylbenzene, and the like.

[0150] Examples of suitable organic photoactive compounds include P3HT:PCBM or PI-4 (commercial active layer ink from infinityPV (Jyllinge, Denmark)), PBF-QxF:Y6 D18:Y6, or D18:Y6:PCBM.

[0151] In other embodiments, the photoactive layer can comprise one or more perovskite photoactive compounds. The term perovskite, as used herein, refers to a material with a three-dimensional crystal structure related to that of CaTiO.sub.3 or a material comprising a layer of material, wherein the layer has a structure related to that of CaTiO.sub.3. The structure of CaTiO.sub.3 can be represented by the formula AMX.sub.3, wherein A and M are cations of different sizes and X is an anion. M is selected from Pb, Sn, Ge, Ca, Sr, Cd, Cu, Ni, Mn, Co, Zn, Fe, Mg, Ba, Si, Ti, Bi, or In and X is selected from at least one of F, Cl, Br or I. In many embodiments, M comprises a metal cation, and more preferably a divalent metal cation such as Ca.sup.2+, Sr.sup.2+, Cd.sup.2+, Cu.sup.2+, Ni.sup.2+, Mn.sup.2+, Fe.sup.2+, Co.sup.2+, Pd.sup.2+, Ge.sup.2+, Sn.sup.2+, Pb.sup.2+, Sn.sup.2+, Yb.sup.2+, and Eu.sup.2+. In some embodiments, the second cation may be selected from Sn.sup.2+, Pb.sup.2+ and Cu.sup.2+. In preferred embodiments, M is selected from Pb, Sn, Ge, Si, Ti, Bi, or In.

[0152] In the unit cell, the A cations are at (0,0,0), the M cations are at (1/2, 1/2, 1/2) and the X anions are at (1/2, 1/2, 0). The A cation is usually larger than the M cation. The skilled person will appreciate that when A, M and X are varied, the different ion sizes may cause the structure of the perovskite material to distort away from the structure adopted by CaTiO.sub.3 to a lower-symmetry distorted structure. The symmetry will also be lower if the material comprises a layer that has a structure related to that of CaTiO.sub.3. Materials comprising a layer of perovskite material are well known. For instance, the structure of materials adopting the K2 iF4-type structure comprises a layer of perovskite material.

[0153] The perovskite semiconductor employed in the present invention is typically one which is capable of (i) absorbing light, and thereby generating free charge carriers; and/or (ii) emitting light, by accepting charge, both electrons and holes, which subsequently recombine and emit light. Thus, the perovskite employed is typically a light-absorbing and/or a light-emitting perovskite. The perovskite semiconductor employed in the present invention may therefore be a perovskite which acts as an n-type, electron-transporting semiconductor when photo-doped. Alternatively, it may be a perovskite which acts as a p-type hole-transporting semiconductor when photo-doped. Thus, the perovskite may be n-type or p-type, or it may be an intrinsic semiconductor. In preferred embodiments, the perovskite employed is one which acts as an n-type, electron-transporting semiconductor when photo-doped.

[0154] In some embodiments, A in AMX.sub.3 comprises an organic cation having the formula (R.sub.1R.sub.2R.sub.3R.sub.4N), wherein: [0155] R.sub.1 is hydrogen, unsubstituted or substituted C1-C20 alkyl, or unsubstituted or substituted aryl; [0156] R.sub.2 is hydrogen, unsubstituted or substituted C1-C20 alkyl, or unsubstituted or substituted aryl; [0157] R.sub.3 is hydrogen, unsubstituted or substituted C1-C20 alkyl, or unsubstituted or substituted aryl; and [0158] R.sub.4 is hydrogen, unsubstituted or substituted C1-C20 alkyl, or unsubstituted or substituted aryl.

[0159] In some embodiments, R.sub.1 in the organic cation is hydrogen, methyl or ethyl, R.sub.2 is hydrogen, methyl or ethyl, R.sub.3 is hydrogen, methyl or ethyl, and R.sub.4 is hydrogen, methyl or ethyl. For instance, R.sub.1 may be hydrogen or methyl, R.sub.2 may be hydrogen or methyl, R.sub.3 may be hydrogen or methyl, and R.sub.4 may be hydrogen or methyl. In some embodiments, F can be a substituent of the alkyl chain attached to N or the sub-alkyl chain from the N.

[0160] In some embodiments, A in AMX.sub.3 comprises an organic cation having the formula (R.sub.5R.sub.6N?CHNR.sub.7R.sub.8), and wherein: [0161] R.sub.5 is hydrogen, unsubstituted or substituted C1-C20 alkyl, or unsubstituted or substituted aryl; [0162] R.sub.6 is hydrogen, unsubstituted or substituted C1-C20 alkyl, or unsubstituted or substituted aryl; [0163] R.sub.7 is hydrogen, unsubstituted or substituted C1-C20 alkyl, or unsubstituted or substituted aryl; and [0164] R.sub.8 is hydrogen, unsubstituted or substituted C1-C20 alkyl, or unsubstituted or substituted aryl.

[0165] Alternatively, the organic cation may have the formula (R.sub.5NH.sub.3).sup.+ wherein: R.sub.5 is hydrogen, or unsubstituted or substituted C1-C20 alkyl. For instance, R.sub.5 may be methyl or ethyl. Typically, R.sub.5 is methyl.

[0166] In some embodiments, the organic cation has the formula R.sub.5R.sub.6N?CHNR.sub.7R.sub.8 wherein: R.sub.5 is hydrogen, unsubstituted or substituted C1-C20 alkyl, or unsubstituted or substituted aryl; R.sub.6 is hydrogen, unsubstituted or substituted C1-C20 alkyl, or unsubstituted or substituted aryl; R.sub.7 is hydrogen, unsubstituted or substituted C1-C20 alkyl, or unsubstituted or substituted aryl; and R.sub.8 is hydrogen, unsubstituted or substituted C1-C20 alkyl, or unsubstituted or substituted aryl. Typically, R.sub.5 in the cation is hydrogen, methyl or ethyl, R.sub.6 is hydrogen, methyl or ethyl, R.sub.7 is hydrogen, methyl or ethyl, and R.sub.8 is hydrogen, methyl or ethyl. For instance, R.sub.5 may be hydrogen or methyl, R.sub.6 may be hydrogen or methyl, R.sub.7 may be hydrogen or methyl, and R.sub.8 may be hydrogen or methyl. The organic cation may, for example, have the formula (H.sub.2N?CHNH.sub.2).sup.+.

[0167] As used herein, an alkyl group can be a substituted or unsubstituted, linear or branched chain saturated radical, it is often a substituted or an unsubstituted linear chain saturated radical, more often an unsubstituted linear chain saturated radical. A C1-C20 alkyl group is an unsubstituted or substituted, straight or branched chain saturated hydrocarbon radical. Typically, it is C1-C10 alkyl, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl or decyl, or C1-C6 alkyl, for example methyl, ethyl, propyl, butyl, pentyl or hexyl, or C1-C4 alkyl, for example methyl, ethyl, i-propyl, n-propyl, t-butyl, s-butyl or n-butyl.

[0168] When an alkyl group is substituted it typically bears one or more substituents selected from substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted aryl (as defined herein), cyano, amino, C1-C10 alkylamino, di(C1-C10)alkylamino, arylamino, diarylamino, arylalkylamino, amido, acylamido, hydroxy, oxo, halo, carboxy, ester, acyl, acyloxy, C1-C20 alkoxy, aryloxy, haloalkyl, sulfonic acid, sulfhydryl (i.e. thiol, SH), d-C10 alkylthio, arylthio, sulfonyl, phosphoric acid, phosphate ester, phosphonic acid and phosphonate ester. Examples of substituted alkyl groups include haloalkyl, hydroxyalkyl, aminoalkyl, alkoxyalkyl and alkaryl groups. The term alkaryl, as used herein, pertains to a C1-C20 alkyl group in which at least one hydrogen atom has been replaced with an aryl group. Examples of such groups include, but are not limited to, benzyl (phenylmethyl, PhCH.sub.2), benzhydryl (Ph.sub.2CH), trityl (triphenylmethyl, Ph.sub.3C), phenethyl (phenylethyl, Ph-CH.sub.2CH.sub.2), styryl (Ph-CH?CH), cinnamyl (Ph-CH?CHCH.sub.2). Typically, a substituted alkyl group carries 1, 2 or 3 substituents, for instance 1 or 2.

[0169] An aryl group is a substituted or unsubstituted, monocyclic or bicyclic aromatic group which typically contains from 6 to 14 carbon atoms, preferably from 6 to 10 carbon atoms in the ring portion. Examples include phenyl, naphthyl, indenyl and indanyl groups. An aryl group is unsubstituted or substituted. When an aryl group as defined above is substituted it typically bears one or more substituents selected from C1-C6 alkyl which is unsubstituted (to form an aralkyl group), aryl which is unsubstituted, cyano, amino, C1-C10 alkylamino, di(C1-C10)alkylamino, arylamino, diarylamino, arylalkylamino, amido, acylamido, hydroxy, halo, carboxy, ester, acyl, acyloxy, C1-C20 alkoxy, aryloxy, haloalkyl, sulfhydryl (i.e. thiol, SH), C1-10 alkylthio, arylthio, sulfonic acid, phosphoric acid, phosphate ester, phosphonic acid and phosphonate ester and sulfonyl. Typically, it carries 0, 1, 2 or 3 substituents. A substituted aryl group may be substituted in two positions with a single C1-C6 alkylene group, or with a bidentate group represented by the formula X(C1-C6)alkylene, or X(C1-C6)alkylene-X, wherein X is selected from 0, S and R, and wherein R is H, aryl or C1-C6 alkyl. Thus, a substituted aryl group may be an aryl group fused with a cycloalkyl group or with a heterocyclyl group. The ring atoms of an aryl group may include one or more heteroatoms (as in a heteroaryl group). Such an aryl group (a heteroaryl group) is a substituted or unsubstituted mono- or bicyclic heteroaromatic group which typically contains from 6 to 10 atoms in the ring portion including one or more heteroatoms. It is generally a 5- or 6-membered ring, containing at least one heteroatom selected from O, S, N, P, Se and Si. It may contain, for example, 1, 2 or 3 heteroatoms. Examples of heteroaryl groups include pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, furanyl, thienyl, pyrazolidinyl, pyrrolyl, oxazolyl, oxadiazolyl, isoxazolyl, thiadiazolyl, thiazolyl, isothiazolyl, imidazolyl, pyrazolyl, quinolyl and isoquinolyl. A heteroaryl group may be unsubstituted or substituted, for instance, as specified above for aryl. Typically, it carries 0, 1, 2 or 3 substituents.

[0170] The perovskite semiconductor layer of the invention typically comprises at least one anion X selected from halide anions and chalcogenide anions. The term halide refers to an anion of a group 7 element, i.e., of a halogen. Typically, halide refers to a fluoride anion, a chloride anion, a bromide anion, an iodide anion or an astatine anion. The term chalcogenide anion, as used herein refers to an anion of a group 6 element, i.e. of a chalcogen. Typically, chalcogenide refers to an oxide anion, a sulphide anion, a selenide anion or a telluride anion. In preferred embodiments, the anion X is selected from at least one of F, Cl, Br or I.

[0171] In some embodiments, the perovskite layer comprises an organo-metal halide perovskite. In these embodiments, the first cation A is an organic cation, more preferably an ammonium group or other nitrogen containing organic cation. This organic cation (A) in this type of perovskite can comprise a large number of organic cations including protonated alkylamines, cycloalkylamines (such as pyrrolidine or cyclohexyl amine) arylamines and aromatic heterocycles (such as pyridine). In some embodiments, A comprises cations having the general formula RCH.sub.2NH.sub.3.sup.+, RC(NH.sub.2).sub.2.sup.+, R.sub.aR.sub.bCH.sub.1NH.sub.3.sup.+, R.sub.aR.sub.bR.sub.cCNH.sub.3.sup.+, R.sub.aR.sub.bNH.sub.2.sup.+, or R.sub.aR.sub.bR.sub.cNH.sup.+, where R, R.sub.a, R.sub.b, R.sub.c comprises H or a substituted or unsubstituted alkyl group or groups, preferably a C.sub.1 to C.sub.6 substituted or unsubstituted alkyl or aryl group or groups. Whilst a number of organo-metal halide perovskite are possible, preferred A of a perovskite compound comprises at least one of CH.sub.3NH.sub.3.sup.+, or HC(NH.sub.2).sub.2.sup.+.

[0172] The resulting perovskite layer preferably comprises an organo-metal halide perovskite. For example, in some embodiments the perovskite layer comprises at least one of CH.sub.3NH.sub.3MX.sub.3 or HC(NH.sub.2).sub.2MX.sub.3, in which, M is selected from Pb, Sn, TI, Bi, or In; and X is selected from at least one of F, Cl, Br or I. In other embodiments, the perovskite comprises an organo-lead halide perovskite, preferably comprising at least one of CH.sub.3NH.sub.3PbX.sub.3 or HC(NH.sub.2).sub.2PbX.sub.3, in which X is selected from at least one of F, Cl, Br or I.

[0173] In some embodiments, in the optoelectronic device of the invention, the perovskite is a perovskite compound selected from CH.sub.3NH.sub.3PbI.sub.3, CH.sub.3NH.sub.3PbBr.sub.3, CH.sub.3NH.sub.3PbCl.sub.3, CH.sub.3NH.sub.3PbF.sub.3, CH.sub.3NH.sub.3PbBrl.sub.2, CH.sub.3NH.sub.3PbBrCl.sub.2, CH.sub.3NH.sub.3PbIBr.sub.2, CH.sub.3NH.sub.3PbICl.sub.2, CH.sub.3NH.sub.3PbCIBr.sub.2, CH.sub.3NH.sub.3PbI.sub.2Cl, CH.sub.3NH.sub.3SnBrl.sub.2, CH.sub.3NH.sub.3SnBrCl.sub.2, CH.sub.3NH.sub.3SnF.sub.2Br, CH.sub.3NH.sub.3SnlBr.sub.2, CH.sub.3NH.sub.3SnICl.sub.2, CH.sub.3NH.sub.3SnF.sub.2I, CH.sub.3NH.sub.3SnClBr.sub.2, CH.sub.3NH.sub.3SnI.sub.2Cl or CH.sub.3NH.sub.3SnF.sub.2Cl.

[0174] Of course, X does not necessarily need to be a single halide. The resulting perovskite layer can include a mixed halide perovskite wherein X in CH.sub.3NH.sub.3MX.sub.3 or HC(NH.sub.2).sub.2MX.sub.3 comprises two or more of F, Cl, Br or I. Accordingly, CH.sub.3NH.sub.3MX.sub.3 could comprise CH.sub.3NH.sub.3MCl.sub.xI.sub.3-x, CH.sub.3NH.sub.3MI.sub.3-xCl.sub.x or similar. It should be appreciated that CH.sub.3NH.sub.3MCl.sub.xI.sub.3-x, CH.sub.3NH.sub.3MI.sub.3-xCl.sub.x or similar can comprise non-stoichiometric materials in which M is selected from at least one of Pb, Sn, Ge, Si, Ti, Bi, or In, preferably M is Pb. In an exemplary embodiment, the perovskite layer is one of the family CH.sub.3NH.sub.3PbCl.sub.xI.sub.3-x. In preferred embodiments, x is close to zero (i.e. very small chloride content). In other embodiments, x=0 providing a tri-iodide perovskite material layer.

Process of Forming Integrated Multilayer Thin-Film Electronic Device

[0175] The integrated multilayer thin-film electronic device of the present invention consists of multiple layers of functional materials, including conductors and semi-conductors. As previously discussed, one of the important factors in forming a multilayer electronic device is consideration of the orthogonal solubility of alternating materials in each layer. For example, a water/alcohol-based ink (polar materials) can be deposited on the layer fabricated from an organic solvent-based ink (non-polar materials) without redissolving underlying layer. The process can repeat and form a multilayer with alternating polarityi.e. polar/non-polar/polar/non-polar materials.

[0176] If an organic-solvent-based conducting paste is deposited on top of the organic thin-film layer, the thin film will be damaged, lose the function and form a conducting channel through the layer. The phenomenon has been the major failure mechanism of printed PV when the interlayer (polar material) has physical defects (i.e. short-circuit formation through pinholes of the water-soluble charge-selective layer).

[0177] The present invention strategically uses the differences in the orthogonal solubility of the different layers in the multilayer structure of a thin-film electronic device to utilise the solubility of at least one layer of that structure to create a create at least one electrically conductive path through a functional layer that is located between the first electrode and the second electrode of adjacent cells (unit devices). Whilst not wishing to be limited to any one theory, the Inventors have utilised the problematic short-circuit formation through organic layers to create conducting paths for electrode interconnections. This alternate interconnection configuration replaces layer patterning for at least one of the functional layers enabling at least one unpatterned organic layer to be used to fabricate modules.

[0178] The present invention can therefore take advantages of the unpatterned coating and scribing approach shown in FIG. 1(c) (described in the background to the invention section) without requiring costly scribing system.

[0179] In photovoltaic or optoelectronic devices, the unpatterned coating is preferable the photoactive layer. The removal of the patterning requirement for the photo-active layer solves many challenges associated in the manufacturing of printed PV and provides design freedom which will create more market opportunities.

[0180] FIG. 3 illustrates the different in configuration between a photoactive device 100 formed using a prior art method using the one of the prior art methods shown in FIG. 1as shown in Figure (a); and a photoactive device 200 formed using a method according to the present invention. The prior art photoactive device shown in FIG. 3(a) includes a patterned photoactive layer, formed using printing, patterning or scribing as previously described on substrate 130. The electrical inter-unit device connection 102 between the back electrode 105 of a first cell (unit device) 103 and transparent electrode 110 of a second cell (unit device) 104 is formed through a patterned gap formed in the photoactive layer 115 and the charge selective layer 120. In comparison, the photoactive device 200 configured according to the present invention (as shown in FIG. 3(b)) includes an unpatterned photoactive layer 215. The electrical inter-unit device connection 202 between the back electrode 205 of a first unit device 203 and transparent electrode 210 of a second unit device 204 is formed through a patterned gap formed in the charge selective layer 220 and at least one micro- or nano-sized electrically conductive path through the unpatterned photoactive layer 215.

[0181] The patterned charge-selective layer 220 along with the differential orthogonal solubility of the charge-selective layer 220 and photoactive layer 215 is used to control selective formation of the one micro- or nano-sized electrically conductive paths through the unpatterned photoactive layer 215 when applying the different layers of the multilayered photoactive device 200.

[0182] The process of forming this electrode interconnection i.e. the electrical inter-cell connection 202 between the back electrode 205 of a first cell 203 and transparent electrode 210 of a second cell 204 is achieved using the following general steps: [0183] 1. The transparent electrode layer 210 is applied on a thin film substrate 230 as a first patterned coating that includes at least two spaced apart first electrode sections 210A and 210B of adjacent cells 203 and 204, formed as rectangles in FIG. 3; [0184] 2. The photoactive layer 215 is applied over the transparent electrode layer 210 as a substantially continuous coating; and [0185] 3. The charge selective layer 220 is applied over the photoactive layer 215 as a patterned coating. The pattern generally comprises at least two spaced apart functional sections 220A and 220B (formed as rectangles in FIG. 3), each functional section 220A and 220B is patterned to be positioned on the photoactive layer 215 to overlay a portion of one of the first electrode sections 210A and 210B so to define a gap portion 235 between adjacent functional sections 220A and 220B that includes a portion of that first electrode section 210 and the transparent electrode layer 210.

[0186] These steps produce an intermediary device that comprises the patterned transparent electrode layer 210, substantially continuous photoactive layer 215 and patterned charge selective layer 220. The photoactive device 200 is completed by applying a back electrode 205 as a patterned coating in the following step: [0187] 4. The back electrode 205 is applied over the charge selective layer 220 as a third patterned coating that includes at least two spaced apart second electrode sections 205A and 205B, each second electrode section 205A, 205B being positioned to overlay at least one functional section 220A and 220B of the charge selective layer 220 and a portion of an adjoining gap portion 235 that includes at least one portion of the first electrode section 210A and 210B of an adjacent cell 203 and 204. The back electrode 205 is formed using a solution including a conductive species and at least a first solvent. In this set up, the gap portion 235 between adjacent functional sections preferably comprises the transparent electrode layer 210 and photoactive layer 215 only.

[0188] The layers and solvents are selected to have differential orthogonal solubility of alternating material layers, such that the photoactive layer 215 is soluble in the first solvent and the charge selective layer 220 has a low to zero solubility in the first solvent. The photoactive layer 215 and the charge selective layer 220s are formulated to have different polarities, with the first solvent having the same polarity as the photoactive layer 215. Thus, where the photoactive layer 215 is a polar layer, the first solvent is a polar solvent. Where the photoactive layer 215 is a non-polar layer, the first solvent is a non-polar solvent. The charge selective layer 220 is a different polarity to the photoactive layer 215.

[0189] In embodiments, the first solvent comprises: [0190] A. DMF, DMSO, Y-butyrolactone, acetone, acetyl acetone, ethyl acetoacetate, NMP, DMAC, THF or combinations thereof; [0191] B. isopropanol, n-butanol, isobutanol, ethanol, methanol, acetic acid, ethylene glycol, propylene glycol, glycerol, allyl alcohol, propargyl alcohol, inositol or combinations thereof; or [0192] C. benzene, toluene, xylene, trimethylbenzenes (for example mesitylene), chlorobenzene, dichlorobenzene, chloroform, dichloromethane, anisole, propylene glycol methyl ether acetate, diethylene glycol mono butyl ether, di(propylene glycol) dimethyl ether or combinations thereof.

[0193] Again, it should be appreciated that selection of the first solvent depends on the required polarity and the composition of the various layers. Where the integrated multi-layer thin film electronic device comprises an optoelectronic device, and in particular a photovoltaic device, selection of the first solvent depends on the composition of the photovoltaic layer. For perovskite devices, the first solvent is preferably selected from either A or B above depending on the polarity of that layer. For organic PV devices, the first solvent is preferably selected from C above.

[0194] The first solvent from the applied composition of the back electrode layer 205 dissolves at least part of the photoactive layer 215 in the gap portion 235, to form an electrical interconnect between the transparent electrode layer 210 and back electrode 205 through the photoactive layer 215. In contrast, the charge selective layer 220 is not affected by the first solvent and does not dissolve on application of the back electrode 205, remaining substantially intact (defect free) when the back electrode 205 is applied. Therefore, application of the back electrode 205 to the gap portion 235 forms one or more (typically a multitude) of micro- to nano-sized electrically conductive paths through the photoactive layer 215 between the back electrode 205 of a first cell 203 and transparent electrode 210 of a second cell 204.

[0195] The present invention therefore provides an alternative process for forming an electrical connection between spaced apart electrodes through the functional layers of an integrated multilayer thin-film electronic device by utilising the selective solubility of components of the multilayer film with the solvent used to form the back electrode 205.

[0196] Whilst only two adjacent cells (unit devices) are illustrated in FIG. 3, it should be appreciated that the photoactive device 200 in FIG. 3 typically comprises a series of adjacent cells on the thin film substrate and may also be arranged in a module. Each adjacent cell can include an interconnect formed according to the present invention.

[0197] Whilst not illustrated, the electrical inter-cell connection 202 is typically formed from a number of nano- to micro-sized channels in the photoactive layer 215. As explained above, these typically comprise one or more defects in the photoactive layer 215, such as a pinhole defect through the thickness of the photoactive layer 215. Typically, the process forms a large number of nano- to micro-paths or channels. In most cases, this conductive path comprises millions of nano- to micro-channels through the photoactive layer 215. For example, a whole area of a 2 mm?100 mm line can be a conductive path, depending on the active layer and conducting paste. In some cases, the whole layer (the photoactive layer 215 uncovered by the charge selective layer 220) can be uniformly conductive. Each of the nano- to micro-paths or channels are distributed through, along and about the photoactive layer 215.

[0198] The composition of the various layers depends on the configuration of the photoactive device 200. As discussed above, the photoactive layer 215 may comprise at least one of one or more organic photovoltaic compounds, or one or more perovskite photo-active compounds, the possible compositions of which are also discussed above. Furthermore, the charge selective layer 220 can comprise at least one of: at least one electrode screening layer; at least one hole blocking layer; at least one electron blocking layer; at least one hole transporting layer; or at least one electron transporting layer, again, the possible compositions of which are also discussed above. In some embodiments, the charge selective layer 220 comprises a hole transporting layer, for example poly(3,4-ethylenedioxythiophene and polystyrene sulfonate mixture (PEDOT:PSS). The transparent electrode layer 210 can comprise any suitably configurable conductive species, for example tin doped indium oxide (ITO), fluoride-doped tin oxide (FTO), doped zinc oxide such as aluminium doped zinc oxide (AZO), or indium doped cadmium-oxide. And finally, the back electrode 205 preferably comprises a metallic electrode, and more preferably a silver electrode formed using a solution including the metal or ionic form of the metal and the first solvent (as discussed above). It should be appreciated that the above compositions should not be limiting on the invention, and other suitable compositions are possible as discussed throughout this specification.

[0199] It also should be appreciated that further layers can be included in the multilayer structure of the device 200 in addition to the layers shown in the device 200 illustrated in FIG. 3. For example, a further charge selective layer (one of a hole transporting layer or an electron transporting layer depending on the configuration of the photoactive device, as illustrated and described in relation to the devices 50, 60 and 70 illustrated in FIG. 2) could be included between the transparent electrode layer 210 and the photoactive layer 215, for example as shown the devices 50 and 60 illustrated in FIGS. 2(a) and (b)). This further charge selective layer would be applied as a fourth patterned coating having a complementary and corresponding pattern to the second patterned coating of the charge selective layer 220 is applied over the photoactive layer 215, also defining a complementary and corresponding gap portion 235 to provide the required overlap of the back electrode 205 of a first cell 203 and transparent electrode 210 of a second cell 204 to facilitate the electrically conductive path through the photoactive layer 215 between these two electrodes.

[0200] It should be appreciated that each of the layers described above in relation to the devices 50, 60 and 70 illustrated and described in relation to FIGS. 2(a), 2(b) and 2(c) and device 200 in FIG. 3 can be applied in the integrated multilayer thin-film electronic device to form the device (see below) as a solution, mixture, admixture, paste or the like in, with or in conjunction with an appropriate carrier solvent. That solvent is selected with the appropriate polarity to fit the differential orthogonal solubility of alternating material layers corresponding with the preferred alternating polarities of the layers. Suitable solvents include: [0201] DMF, DMSO, Y-butyrolactone, acetone, acetyl acetone, ethyl acetoacetate, NMP, DMAC, THF or combinations thereof; or [0202] isopropanol, n-butanol, isobutanol, ethanol, methanol, acetic acid, ethylene glycol, propylene glycol, glycerol, allyl alcohol, propargyl alcohol, inositol or combinations thereof.

[0203] As previously discussed, the various layers can be applied to form the integrated multilayer thin-film electronic device 200 using a variety of application techniques. In some embodiments, at least one of the transparent electrode layer 210, photoactive layer 215, charge selective layer 220 or back electrode 205 is applied to the substrate using at least one of: casting, doctor blading, printing, screen printing, inkjet printing, pad printing, knife coating, meniscus coating, slot die coating, gravure coating, reverse gravure coating, kiss coating, micro-roll coating, curtain coating, slide coating, spray coating, flexographic printing, offset printing, rotatory screen printing, or dip coating.

[0204] Each applied layer of the integrated multilayer thin-film electronic device 200 can also undergo a drying process/step to assist the layer drying. The drying step can comprise any number of drying process including one or a combination of air dry, convective drying, ambient drying, heat treatment, annealing, quenching, or the like. In some embodiments, drying the applied layer includes heat treatment of the applied layer at a temperature of at least 60? C., preferably at least 70? C., more preferably at least 100? C., and yet more preferably at least 120? C.

Design Freedom for High Performance and Aesthetics

[0205] The key advantage of solution-processed thin-film electronic devices is the potential manufacturing by low-cost roll-to-roll printing. Roll-to-roll production of printed organic PV has been previously demonstrated by several groups, including the Applicant.

[0206] FIGS. 4(a) and 4(b) show examples of roll-to-roll produced printed PV, with the film movement direction going from left to right in the Figures, as shown by arrow 302. The design 300 shown in FIG. 4(a) shows series-connected module designs developed by InfinityPV. This design allows cut-to-size for the required output voltage. The design 320 shown in FIG. 4(b) provides the freedom to set output voltage and current. The devices shown in FIGS. 4(a) and 4(b) can be produced using the method of the present invention.

[0207] Although the modules offer flexibility and advantages over conventional rigid solar cells, cells are made in parallel to the production direction due to the limitation of the production method. Such designs require inter-module linkers/gaps for large-area applications and result in GFF loss due to the non-active areas.

[0208] The interconnection produced using the method of the present invention allows greater flexibility in device design, such as the device 330 in FIG. 4(c). The device shown in FIG. 4(c) is patterned with cells 332 configured as laterally spaced apart rectangles positioned lengthwise perpendicular to the longitudinal axis L-L of the longitudinal length of the substrate film on which the cells 332 are printed, producing a module with the perpendicular cell design. Series connections between adjacent cells 332 can be made infinitely throughout the film using the interconnection process of the present invention without area-loss for the inter-module connections. Any part of the film can be cut for the required application area or output voltage. If all modules have the same cell-area efficiency, the module with the perpendicular design would have higher power output compared to conventional layout (for example as shown in FIGS. 4(a) and 4(b)) simply due to a larger fraction of cell-area.

[0209] Process and device configuration of the present invention not only provides higher performance at low cost but also offers design freedom. An example of one device 400 comprising a module having a perpendicular cell design set up is shown in FIG. 5(a). These devices 400 can have much more plain looking from the front (substrate side). However, depending on thickness or material, the device 400 can be completely opaque without any pattern or semi-transparent as shown in FIG. 4. However, as will be explained in more detail below, images such as the CSIRO logo (as shown in FIG. 5(a)) can be added in the module. A conventional module 410 is shown in FIG. 5(b) for comparison. Although the longitudinally aligned stripe pattern (with respect to the longitudinal axis of the film) can be aesthetic in certain design/application, this longitudinal stripe pattern can limit the commercial application of printed PV.

[0210] A non-conventional module design 420 reported by Belectric OPV GmbH (currently OPVIUS) is also shown in FIG. 5(c). The module design 420 was fabricated by Belectric OPV GmbH using laser scribing to make the physical gap. It should be appreciated that this module design could also be fabricated using embodiments of the process of the present invention.

Printed Indicia

[0211] The first patterned coating of the transparent electrode layer 210 and the second patterned coating of the charge selective layer 220 can have any suitable configuration. In FIGS. 3, 4(c), 5(a) and 6(a), 6(b), 6(c) the first patterned coating comprises a plurality of spaced apart discrete rectangular first electrode sections 210A, 210B arranged in a regular pattern on the thin-film substrate 230. Each electrode section 210A, 210B has the same shape. The second patterned coating comprises a complimentary rectangular grid pattern to the first patterned coating.

[0212] In the embodiments shown in FIGS. 6(a), 6(b) and 6(c) the first patterned coating and second patterned coating comprise a plurality of spaced apart rectangular sections having a first longitudinal axis Y-Y applied to the substrate 230 so that the length of the rectangular section run width-wise on the substrate 230 and such that the rectangular sections are spaced apart and aligned lengthways along the second longitudinal axis L-L, which follows the length of the substrate 230.

[0213] The back electrode 205 can be designed by screen printing narrow solid lines of the back electrode composition onto the dried charge selective layer 220, for example as shown in FIGS. 4(c) and 6(a)(i). Greater detail of the possible print patterns is illustrated in FIG. 6(a). In each of these embodiments, the back electrode 205 is printed to include gap portions, for example as a grid or spaced apart lines. As shown in FIG. 6(a)(i), the lines of the back electrode 205 in each cell 505 can be arranged as a set of homogenous lines. However, greater design freedom can be achieved by using different line thicknesses and therefore varying the overall device transparency. Moreover, more design freedom in the pattern can be achieved by printing the back electrode 205 coating (the third patterned coating) as a grid 515, 525, 535 formed from a regular repeating geometric shape, such as a hexagon as shown in the devices 510, 520, 530 in FIGS. 6(a)(ii), 6(b) and 6(c).

[0214] A highlighted pattern can then be rendered in this grid 525, 535, such the CSIRO brand (Figures, 5(a) and 6(b)) by highlighting sections of that grid 525, 535 by using thicker/wider lines in portions of the grid 525, 535 compared to other portions of the grid 525, 535. Those highlighted parts can be designed to form patterns within the grid 525, 535, which when the grids 525, 535 are designed to have a contrasting shade and/or colour to the underlying layers, can produce a visual and/or visible pattern disenable to a viewer of the integrated multilayer thin-film electronic device. That visual and/or visible pattern can comprise a pattern, picture, indicia such as logos, letters, numbers, symbols, patterns, rendered images, one or more words, signs, marks, emblems, tag, seal, stamp or the like. In certain embodiments, the thickness/width of the selected portions of elements in the grid 525, 535 are at least 1.5 time, preferably 2 times the thickness of adjoining elements in the grid 525, 535. However, it should be appreciated that any suitable thickness/width difference may be used that provides a discernible rendering of the selected indicia.

[0215] As shown in FIG. 6(b), a logo such as CSIRO logo can be rendered by varying the thickness of the lines in the grid 525 to produce a darker pattern that renders the letters making up CSIRO. As shown in FIG. 6(c), gradient images can also be achieved by varying the thickness/width of the lines in the grid 535 to produce different shades.

[0216] In order to assist in rendering the selected indicia in the grid 525, 535, the colour of the second electrode layer is preferably selected to contrast with the first functional layer and second functional layer. That colour is preferably selected to produce high-contrast lines relative to the colour of the first functional layer and second functional layer.

[0217] It should be appreciated that the images and indicia could be produced on any regular repeating grid of lined third patterned coating, for example using the more conventional stripe design shown in FIG. 6(a)(i). However, it is possible that these patterns may introduce high-contrast lines that can detract from the image or indicia trying to be rendered.

EXAMPLES

Example 1Organic Photovoltaic Modules

[0218] Roll to Roll (R2R) processed organic photovoltaic (OPV) modules comprising multiple series-connected strip cells in an inverted configuration were fabricated on an ITO-coated PET film (8?/sq, OPV8, Solutia) to give a device consisting of PET|ITO|PEIE|Pi-4|PEDOT:PSS|Ag. An indium tin oxide-polyethylene terephthalate (ITO-PET) substrate with a perpendicular-module design 10 mm wide ITO pattern with 1 mm wide gaps were used. The device configuration was therefore: flexible ITO/PEIE (electron selective layer)/PI-4 (commercial photoactive ink)/S315 (commercial PEDOT:PSS ink, hole selective layer)/PV-416 (commercial silver paste).

[0219] The module was coated as follows:

[0220] An aqueous solution of PEIE (Mw 70,000 g/mol, 35-40% w/w, Aldrich) was diluted with 2-methoxy ethanol to a concentration of 0.15% w/w. This solution was coated onto ITO-coated PET film by the reverse-gravure coating method using a Mina-Labo? coater (Yasui Seiki Co. Ltd) to form a PEIE film having an estimated thickness of around 10 nm. Both the PEIE and active polymer light-absorbing layers were deposited on the reverse-gravure(RG) coater were coated on ITO-PET substrates using a 200 R roll with a coating width of 10 cm. The coating was carried out at 1.0 m/min speed and 4 rpm of RG roll speed. The PEIE layer was dried by hot air at 110? C. for ?7 s and annealed on a curved hot plate at 140? C. for ?7 s.

[0221] The Pi-4 (InfinityPV ready-made active ink) polymer absorber layer (?100 nm thick) was coated at 1.0 m/min web speed and 5.5 rpm of roll speed. During the active layer deposition, the film was dried only using hot air at 90? C. for ?7 s and on a curved hot plate at 90? C. for ?7 s.

[0222] Roll to roll (R2R) Deposition of PEDOT: PSS strips and the Ag grid were carried out using the screen-printing method on an Orthotec-2 R2R screen printing system with a drying step using hot air at 100? C. and IR radiation (30% intensity) for ?20 s. PEDOT:PSS was screen printed twice to form a pinhole-free layer using a screen-printable paste continuing S315 (Agfa) and ORGACON Screen-print Ink (Agfa) PEDOT:PSS materials with the ratio of 1:9 mixed for over 10 minutes using high shear mixer (ULTRA-TURRAX T25, IKA Labortechnik).

[0223] To enhance charge collection of the module and to establish the interconnection between the 20 cells in series, a screen-printed grid was deposited using a commercially available Ag ink (DuPont, PV416, 2021). The Ag ink has co-solvents consisting of two alkyl esters: pentanedioic acid dimethyl ester (Dimethyl glutarate) and butanedioic acid dimethyl ester (Dimethyl succinate). Based on GC-MS analysis, dimethyl glutarate is the major solvent in the Ag ink. Each deposited layer had 0.2 to 0.5 mm offset from the under-laying layer so that series-connection could be made. The screen-printed Ag grid was dried using hot-air at 100? C. and IR radiation (30% intensity) for ?20 s. The active area of each strip cell is 8.1 cm.sup.2 (width: 0.9 cm and length: 9 cm) resulting in total active module area of ?162 cm.sup.2.

[0224] The device characteristics of the module are shown in FIG. 6. FIG. 6. Example current density (per cell area rather than the whole module area for comparison)-voltage characteristics of a single PV cell and a perpendicular-module with 19 cells in series connection.

[0225] Only commercial solutions are used in the demonstration example without modifications. However, it should be appreciated that the solutions, such as the conductive inks can be modified for the increased channel-forming property by adding good solvents for the photo-active layer.

[0226] Whilst the above disclosure and example relates to optoelectrical devices, specifically photovoltaic devices, it should be appreciated that the present invention can be applied to many other solution-processed integrated multilayer thin-film electronic devices such as organic transistors, OLEDs, organic memories and printed sensors. In these devices, the differential orthogonal solubility of alternating material layers and selected patterning of layers taught in relation to the process of the present invention can be utilised in a similar manner to form an electrical interconnection between two spaced apart electrode layers within the multilayer structure thereof.

[0227] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is understood that the invention includes all such variations and modifications which fall within the spirit and scope of the present invention.

[0228] Where the terms comprise, comprises, comprised or comprising are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other feature, integer, step, component or group thereof.