POLYPHENOLS AND POLYAMINO DERIVATIVES IN ORGANIC OPTOELECTRONIC COMPONENTS

Description

Field of invention

[0001] The invention describes optoelectronic components, specifically organic optoelectronic components, with polyphenols and polyamino derivatives. State of the art

[0002] Organic optoelectronic devices, such as solar cells, enable the conversion of light into electricity using the photoelectric effect. This conversion requires organic semiconductor materials with sufficiently good absorption properties. These absorber materials are preferably small organic molecules whose optical and electronic properties depend strongly on their orientation.

[0003] To fabricate efficient organic photoactive devices, these often consist of several stacked cells in a tandem or multilayer structure between two electrodes. The photoactive layers—that is, the layers of a cell that absorb light and contribute to current generation—can also consist of multiple layers. In addition to the photoactive layers, the organic optoelectronic device can also include, for example, doped and undoped charge carrier transport layers and / or passivation layers within a cell. Small-molecule donor and acceptor materials can be used as photoactive materials. The inventors define the absorber materials as small-molecule oligomers. These oligomers are preferably acceptor-donor-acceptor' or donor-acceptor-donor' oligomers with at least one extended donor or extended acceptor block, respectively.These absorber materials comprise a well-defined number of monomers, typically fewer than ten, and have a well-defined mass, typically less than 1500 g / mol, preferably less than 1200 g / mol. They are free of undefined, potentially reactive end-chain groups such as those that can occur as byproducts of polymerization chain reactions in polymers. Advantages of these small-molecule-based absorber materials include their evaporability in a vacuum and the associated possibility of purification by gradient sublimation. This allows for the fabrication of arbitrarily complex multilayer systems by sequentially evaporating different and pure materials. These absorber materials also enable photoactive heterojunctions (see WO 2006 092 134).A photoactive layer in a photoactive layer stack of a cell can comprise only an acceptor or only a donor absorber material, or it can comprise a combination of several absorber materials of different types. Furthermore, materials can be added to the absorber layers to improve their absorption properties. For example, absorber materials based on small molecules are described in WO 2006 092 134, WO 2011 161 262, and WO 2014 128 277. Organic optoelectronic devices are disclosed, for example, in WO 2004 083 958 and WO 2011 138 021.

[0004] Particularly strong light absorption is achieved when the molecular transition dipole moments of the absorber molecules are aligned orthogonally to the incident light wave. Besides light absorption, the charge transfer from the absorber molecule to the adjacent layers towards the electrodes is also important. This transfer becomes especially large when the pi-electron systems present in the absorbers overlap with the pi-electron systems of the underlying layer. This arrangement is referred to as "face-on." This arrangement is preferred. In contrast, the arrangement referred to as "edge-on" is preferred, in which, although the molecular dipole is orthogonal to the incident light wave as in "face-on," the pi-electron systems of the absorber are aligned orthogonally to the underlying layer, thus suppressing effective charge transfer between the pi-electron systems.The growth of absorber materials on substrates or other layers is determined by intermolecular forces, which dictate both the growth direction and the orientation of the adjacent molecules relative to each other. For this purpose, it is possible to insert an orientation-defining layer, also known as a template layer.

[0005] The inventors have found that certain absorber materials, predominantly donor materials, can have problems with "face-on" orientation, i.e., orientation orthogonal to the incident light wave. Such donor materials include, for example, heterocyclic rings such as phthalocyanines, thiophene, furan, and / or pyrrole rings, and are preferably acceptor-donor-acceptor compounds, as disclosed, for example, in WO 2006 092 134. Due to the frequently non-face-on growing orientation of the absorber materials, optimal utilization of these absorber materials is not achieved in solar cells manufactured with them.

[0006] WO 2011 025 567 discloses organic optoelectronic devices consisting of a structure-forming layer on an electrode layer, onto which a photoactive layer system of acceptor and donor molecules is then deposited, such that the adjacent structure-forming layer ensures an ordered molecular alignment of the acceptor or donor material. WO 2011 025 567 proposes acenes, perylenes, for example diindenoperylene (DIP) or 3,4,9,10-perylene tetracarboxylic acid dianhydrides (PTCDA), polyphenylenes, or coronene as structure-forming materials.

[0007] US 2002 098 346 discloses multilayer structures on a substrate, wherein a first monomolecular layer contains a first structure-forming material and defines the orientation of this layer, and wherein a chemically reactive monomer leads to a directed chemical reaction on the surface, thereby achieving an ordered molecular structure. Therefore, the applicability of US 2002 098 346 is limited to substances that can react chemically. It is not applicable to pure physisorption without a chemical reaction.

[0008] WO 2010 044 122 discloses organic solar cells based on dyes that induce a photoelectrochemical reaction. [Ramaoorthy, R. et al.: Betalain and anthrocyanin dye-sensitized solar cells. J. Appl. Electrochemica. (2016) 46-929-941.] and [Kumara GRA et al.: Shiso leaf pigments for dye-sensitized solid-state solar cells. Solar Energy materials & Solar cells 90 (2006) 1220-1226.] also disclose dye-sensitized solar cells made with natural dyes, in which, for example, a TiO₂ layer is immersed in the dye solution. They thus reveal that the natural dyes absorb light in conjunction with TiO₂.

[0009] US 2009 / 159120 A1 discloses quantum dot solar cells with conjugated bridged molecules. Alizarin is proposed as a compound for a "bridge layer 14" located between a transport layer and a quantum dot layer. However, the "bridge layer 14" is not a template layer directly adjacent to a photoactive layer. Description of the invention Technical task

[0010] The aim of the presented invention is to provide materials that lead to an improved orientation of the absorber molecules based on small molecules in the photoactive layer, also referred to as absorber layer, and thus enable an increase in the short-circuit current, while at least not reducing the open-circuit voltage of the optoelectronic device. Disclosure of the invention and technical effect of the invention

[0011] The technical problem is solved by the use of polyphenols and / or polyamino-aromatics or -heteroaromatics adjacent to absorber materials in organic optoelectronic devices, as defined in the claims, to achieve better face-on growth of the absorber materials.

[0012] Due to the limitation of US 2002 098 346 in its applicability to substances that can react chemically, it is not applicable to pure physisorption without chemical reaction, which is the basis of the present invention.

[0013] The term "face-on" refers to the case in which the pi-electron systems of the materials of the polyphenol layer and / or polyamino derivative layer used form a pi-pi overlap with the pi-electron system(s) of the subsequent absorber layer.

[0014] Optoelectronic components are described that comprise connections of structure (I) adjacent to absorber materials: where A symbolizes the remainder of a cycle that forms wholly or partly a carbocyclic or heterocyclic aromatic, monocyclic or polycyclic system, wherein this cycle comprises at least n > 1 residues RA, and these residues RA are each independently selected from hydroxy and amino groups.

[0015] Compounds whose RA residues are selected from hydroxyl groups are also described and used in organic optoelectronic devices. The compounds used are preferably those of general structure II: the two or more linked aromatic or heteroaromatic rings (Ar1, Ar2), preferably benzene rings, each comprising at least two hydroxyl groups and / or amino groups, wherein the aromatic rings (Ar1, Ar2) may be linked by a single bond (-X-) or directly fused, R1 to R6 being selected from H, OH, NH2; Y1 being selected from CH, CH2, CO; Y2 being selected from CH, CH2, CO, H; Z1 being selected from CH, CH2, CO, O, NH; Z2 being selected from CH, CH2, CO, O, NH, H; wherein the links Y1 ... Z1 and / or Y2 ... Z2 may be of a covalent or non-covalent nature, wherein in the first (covalent) case Y1 ... Z1 and / or Y2 ... Z2 may also form a substituted aromatic or heteroaromatic mono-, di- or trihydroxy compound.

[0016] The fused structures are preferably substituted naphthalene derivatives (II.1) and anthracene derivatives (II.2), which can be either bridged or unbridged. If YI, ZI, or RI with I > 1 are not explicitly assigned to a position, the substituents can be located at any position in the assigned ring. wherein R1 to R6 are selected from H, OH, NH2; Y1 is selected from CH, CH2, CO; Y2 is selected from CH, CH2, CO, H; Z1 is selected from CH, CH2, CO, O, NH; Z2 is selected from CH, CH2, CO, O, NH, H; wherein the linkages Y1 ... Z1 and / or Y2 ... Z2 can be of a covalent or non-covalent nature, wherein in the first (covalent) case Y1 ... Z1 and / or Y2 ... Z2 can also form a substituted aromatic or heteroaromatic mono-, di- or trihydroxy compound.

[0017] The bridging of the aromatic rings (Ar1 and Ar2) according to structure (II), which are linked by a single bond (-X-), can occur independently by one or two double bonds forming a phenanthrene or pyrene, by one or more fused aromatic or heteroaromatic rings forming a triphenylene or dibenzopyrene, by alkyl groups with one to three carbon atoms, by aryloxy or arylamino groups, by alkoxy groups forming pyrans, by carbonyl, carboxy or carbamoyl groups forming ketones, quinones, anthraquinones (II.3), lactones and lactams. wherein Ar1 and Ar2 are two or more linked aromatic or heteroaromatic rings (Ar1, Ar2), preferably benzene rings, each comprising at least two hydroxyl groups and / or amino groups, R1 to R6 being selected from H, OH, NH2; Y1 being selected from CH, CH2, CO; Y2 being selected from CH, CH2, CO, H; Z1 being selected from CH, CH2, CO, O, NH; Z2 being selected from CH, CH2, CO, O, NH, H; wherein the linkages Y1 ... Z1 and / or Y2 ... Z2 can be of a covalent or non-covalent nature, wherein in the first (covalent) case Y1 ... Z1 and / or Y2 ... Z2 can likewise form a substituted aromatic or heteroaromatic mono-, di- or trihydroxy compound.

[0018] The technical problem is solved according to the invention by providing an organic optoelectronic device comprising two electrodes and at least one photoactive layer system arranged between them, the latter comprising at least one photoactive layer comprising absorber materials based on small molecules, wherein the absorber material is ADA molecules, wherein the photoactive layer is adjacent to a template layer, wherein the template layer comprises a compound of structure (II.1), (II.2), (II.3) and / or (II.4), wherein: Ar1 and Ar2 are two or more linked aromatic or heteroaromatic rings (Ar1, Ar2), preferably benzene rings, each comprising at least two hydroxyl and / or amino groups, R1 to R6 being selected from H, OH, NH2; Y1 being selected from CH, CH2, CO; Y2 being selected from CH, CH2, CO, H; Z1 being selected from CH, CH2, CO, O, NH; Z2 being selected from CH, CH2, CO, O, NH, H; wherein the links Y1 ... Z1 and / or Y2 ... Z2 are both covalent and non-covalent in nature, wherein in the first (covalent) case Y1 ... Z1 and / or Y2 ... Z2 can also form a substituted aromatic or heteroaromatic mono-, di- or trihydroxy compound.

[0019] Preferred compounds according to the invention based on polyphenols are understood to be, in particular, compounds of the general structure (II.4), especially preferably ellagic acid.

[0020] The compounds used according to the invention, based on polyamino derivatives, are in particular understood to be the following: Polyamino-aromatic or -heteroaromatic compounds described by the general structure (I) wherein A symbolizes the remainder of a cycle which forms wholly or partly a carbocyclic or heterocyclic aromatic, monocyclic or polycyclic system, and wherein this cycle comprises at least 2 amino groups.

[0021] As a further solution to the technical problem, the production of organic optoelectronic components comprising one of the compounds according to the invention of polyphenols and / or polyamino-aromatics or -heteroaromatics adjacent to absorber materials based on small molecules.

[0022] According to the invention, the following is used to manufacture the organic optoelectronic component during the production of the layers of the organic optoelectronic component. a) before applying at least one absorber layer, the template layer comprising the at least one compound of structure (II.1), (II.2), (II.3) and / or (II.4) is applied to previously deposited layers, and / or b) simultaneously with the absorber materials of the at least one absorber layer, the at least one compound of structure (II.1), (II.2), (II.3) and / or (II.4) is applied to previously applied layers. Advantageous effect of the invention

[0023] By using the structures according to the invention as a template layer, the adjacent absorber material applied after the template layer is better aligned, resulting in improved efficiency of the optoelectronic component.

[0024] For multilayer OPV (organic photovoltaics), a face-on orientation of the molecules is achieved, ensuring optimal light absorption and improved charge transport properties. In OPV devices, the generation of crystalline order can lead to an increase in the short-circuit current (Isc) and the open-circuit voltage (Voc). Thus, by controlling the molecular crystalline orientation of the absorber layers, especially the donor layer, the frontier orbital levels, absorption coefficient, morphology, and exciton diffusion lengths can be optimized. This improves the efficiency of energy conversion. A pi-stack arrangement of coplanar, flat-lying absorber molecules, extending over several layers (face-on growth), is therefore highly desirable and is promoted by the compounds according to the invention adjacent to the absorber materials.

[0025] To achieve optimum donor molecule orientation and morphology, the template-donor molecule interaction should be strong enough to achieve face-on stacking, yet weak enough to avoid film roughness. In particular, charge transport perpendicular to the substrate should be improved, which increases the fill factor or, with a constant fill factor, allows for greater layer thicknesses, thus generating more photocurrent.

[0026] The use of the compounds with the above substituent pattern according to the invention forms layers with flat-lying molecules (face-on, horizontal orientation) via strong hydrogen bonds and with simultaneously weakened pi-stacking interaction, in contrast to phthalocyanines, hexabenzocorons and other multiply aromatically and heteroaromatically fused disc molecules, in which the strong pi-pi stacking interaction of the molecules among themselves causes them to be coplanar and to stand upright vertically (edge-on, vertical orientation).

[0027] The inventors demonstrate, using the example of a template layer comprising ellagic acid, which represents one of the compounds according to the invention in accordance with one of the structures mentioned above, and which was applied to the layer stack in front of the absorber layer, that solar cells with a template layer have a higher efficiency than adequate solar cells without a template layer.

[0028] Furthermore, the inventors were surprised to discover that solar cells with only a thin template layer have a higher efficiency than identical solar cells without a template layer, and that the lifespan of the solar cells can be increased at the same time. (Brief description of the drawings)

[0029] The invention and its embodiments are described with drawings. The individual drawings depict: Fig. 1: X-ray diffractogram of a template layer. Fig. 2, Fig. 3, Fig. 4: X-ray diffractograms of samples with and without a template layer. Fig. 5, Fig. 6, Fig. 7, Fig. 8: Current-voltage curves of solar cells with and without a template layer. Fig. 9: Accelerated lifetime measurement of solar cells with and without a template layer. Fig. 10: List of absorber material molecules mentioned in the exemplary embodiments. Fig. 11: 2D arrangements of possible additional materials in a template layer. Detailed description of the invention

[0030] The technical problem is solved by using polyphenols and / or polyamino-aromatics or -heteroaromatics adjacent to small molecule-based absorber materials in organic optoelectronic devices to achieve better face-on growth of the absorber materials.

[0031] Similarly, the technical problem is solved by a layer comprising polyphenols and / or polyamino-aromatics or -heteroaromatics, wherein the layer with these compounds adjoins absorber layers with absorber materials based on small molecules and enables better face-on growth of the absorber materials.

[0032] The technical problem is thus solved according to the invention with organic optoelectronic devices comprising two electrodes and at least one photoactive layer system arranged between them, this comprising at least one photoactive layer, comprising absorber materials based on small molecules, wherein the absorber material is ADA molecules, wherein the photoactive layer is adjacent to a template layer, wherein the template layer comprises a compound of structure (II.1), (II.2), (II.3) and / or (II.4), wherein: Ar1 and Ar2 are two or more linked aromatic or heteroaromatic rings (Ar1, Ar2), preferably benzene rings, each comprising at least two hydroxyl and / or amino groups, R1 to R6 being selected from H, OH, NH2; Y1 being selected from CH, CH2, CO; Y2 being selected from CH, CH2, CO, H; Z1 being selected from CH, CH2, CO, O, NH; Z2 being selected from CH, CH2, CO, O, NH, H; wherein the links Y1 ... Z1 and / or Y2 ... Z2 are both covalent and non-covalent in nature, wherein in the first (covalent) case Y1 ... Z1 and / or Y2 ... Z2 can also form a substituted aromatic or heteroaromatic mono-, di- or trihydroxy compound.

[0033] According to the invention, the organic optoelectronic devices are connected to at least one of the compounds proposed according to the invention and are adjacent to absorber materials based on small molecules, or to absorber materials based on ADA (acceptor-donor-acceptor) or DAD (donor-acceptor-donor). The photoactive layers comprising the absorber materials can be configured as A combination of single layers, wherein a layer with a donor material adjoins at least one layer with an absorber material, or are designed as bulk heterojunction layers, or a combination of both.

[0034] In one embodiment, the optoelectronic component comprises a separate layer, referred to as a template layer, comprising the compounds used according to the invention, wherein this template layer was processed prior to the adjacent photoactive layer (absorber layer), comprising at least one absorber material based on small molecules.

[0035] In a further embodiment, within a tandem or multilayer element, only one cell may comprise one of the proposed compounds, or at least two cells may use the same and / or different proposed compounds.

[0036] In a combination of the above embodiments, it is possible that a subcell may also comprise several template layers within its photoactive layer stack, wherein the template layers may comprise the same or different materials.

[0037] Preferred compounds according to the invention based on polyphenols are in particular understood to be compounds of the general structure (II.4).

[0038] The compounds used according to the invention, based on polyamino derivatives, are in particular understood to be the following compounds: Polyamino-aromatics or -heteroaromatics, described by the general structure (I) wherein A symbolizes the residue of a cycle which forms wholly or partly a carbocyclic or heterocyclic aromatic, monocyclic or polycyclic system, and wherein this cycle comprises at least 2 residues based on amino groups.

[0039] Examples of polyphenols used according to the invention are shown in Table 1.

[0040] The following compounds are listed as further usable compounds according to structure (I):

[0041] Most of the compounds listed in the two tables are known and commercially available.

[0042] Likewise, the following natural substances appear suitable as compounds for solving the technical problem, because they also favor a corresponding arrangement:

[0043] Furthermore, the following materials are disclosed, which are characterized by a combination of several OH groups and several NH bridges per molecule. Fig. 11 The 2D arrangement of some materials is illustrated in Table 4 below.

[0044] Furthermore, according to the invention, organic optoelectronic devices are fabricated with compounds according to one of the structures (II.1), (II.2), (II.3), or (II.4). The steps for fabricating organic optoelectronic devices are known to those skilled in the art. Therefore, the invention includes the additional step of applying a template layer, comprising at least one of the compounds according to the invention, to the previously processed layer stack before applying at least one absorber layer. This step can be repeated for further absorber layers within a layer stack of the optoelectronic device, both within a single cell and in different cells, whereby different or identical materials can be used in the template layers.

[0045] Alternatively, at least one compound according to the invention can also be applied together with one or more absorber layers.

[0046] The application of the compounds according to the invention can, for example, by evaporation before applying the absorber layer, when used as a template layer, or by application from a solution take place.

[0047] A template layer containing at least one of the compounds can be applied either in a single cell of a tandem or multiple cell, or in multiple cells of a tandem or multiple cell, prior to the application of the absorber material in that cell. In the individual cells, the same template materials or different template materials can be applied prior to the application of the absorber materials in that cell during the build-up of the layer stack.

[0048] In a further embodiment, the organic optoelectronic component within a cell of a single, tandem or multiple cell comprises several layers with identical or different compounds according to the invention.

[0049] Furthermore, according to the invention, the compounds according to structures (II.1), (II.2), (II.3) or (II.4) are used in organic optoelectronic devices, wherein these materials border on at least one absorber material of a photoactive layer.

[0050] The use of compounds according to the structure (II.4) or compounds according to Table 1 is preferred, the use of ellagic acid is particularly preferred.

[0051] In one embodiment, at least one of the aforementioned materials is used in a template layer that is directly adjacent to a subsequently applied absorber layer.

[0052] Particularly preferred is the use of only one material used according to the invention in a template layer bordering a subsequently applied absorber layer. Examples of implementation

[0053] In the following exemplary embodiments, the functional suitability of the compounds according to the invention is shown using ellagic acid as an example.

[0054] Fig. 1 This shows the result of grazing incidence X-ray diffraction (GIXRD) of a 5 nm thick polyphenol-containing layer. The layers were deposited in a vacuum on a silicon wafer coated with 10 nm C60.

[0055] The separation of the in Fig. 1The layer used as a template was prepared at room temperature. The three Bragg reflections at 2θ of 10.9°, 18.2° and 20.7° are assigned to the face-centered cubic (fcc) phase of the C60 sublayer [Elschner, C. et al.: Determining the C60 molecular arrangement in thin films by means of X-ray diffraction. Journal of Applied Crystallography, 44(5):983-990, 2011].

[0056] The reflection at 27.6° is attributed to the template layer and indicates that it grows nanocrystalline in pi-pi stacks on C60. The distance between the crystal planes corresponds to 3.23 Å. Thus, the template molecules are aligned parallel to the substrate, and the pi-pi stacking direction is perpendicular to the substrate.

[0057] In Fig. 2 The results of GIXRD measurements on a 30 nm donor:C60 mixed layer with the ADA oligomer DCV4T-Et2 are shown below. Fig. 10The donor layer, deposited on a 10 nm C60 / Si substrate, is shown with and without a 5 nm template layer. The donor:C60 mixed layer was deposited at a substrate temperature of 40°C, with a mixing ratio of 2:1 wt%. This mixed layer grows nanocrystalline on C60.

[0058] The reflection at 2θ = 10.8° was assigned to the donor and corresponds to an interplane distance of 8.2 Å. This value indicates donor molecules that are oriented obliquely, i.e., edge-on to the substrate [Guskova, O.: Light absorption in organic solar cells: The importance of oriented molecules, J. Phys. Chem. C, 2013, 117 (33), pp 17285-17293]. Since the (111) reflection of C60 is at 2θ = 10.8°, the detected reflection at 10.8° could also represent a superposition of the donor and C60 reflections. The X-ray diffractogram of the mixed layer grown on the template layer shows the reflection characteristic of the template molecule ellagic acid at 27.6° (cf. Fig. 1The donor reflection at 2θ = 10.8° is no longer present or is significantly attenuated. Instead, the diffractogram shows a new strong reflection at 2θ = 26.1° and a shoulder at 24.6°. The crystal plane distance for the reflection at 26.1° corresponds to 3.4 Å, thus indicating face-on growth or at least a strongly tilted orientation of the donor molecules towards the substrate. The mean size of the donor crystallites was evaluated using the Scherrer equation and is 8.1 nm.

[0059] Thus, the measurement results prove that the orientation of the donor molecules was influenced by the template layer and that the crystallinity of the donor phase in the mixed layer was improved.

[0060] Fig. 3This figure shows measurement results from GIXRD investigations of zinc phthalocyanine (ZnPc) mixed with C60 in a ZnPc:C60 mixed layer, grown on a 10 nm C60 / Si substrate with and without a 5 nm template layer. The 30 nm thick mixed layers were deposited on a substrate heated to 70°C, with a mixing ratio of 1:1. For both samples, the three characteristic reflections of the face-centered cubic (fcc) phase of the C60 sublayer at 2θ = 10.9°, 18.2°, and 20.7° are clearly visible. The ZnPc:C60 mixed layer deposited directly on C60 shows two amorphous ZnPc signals at 2θ = 7.7° and 2θ = 28.6°. In the sample deposited on the template layer, the characteristic disappears at 7.7° and new Bragg reflections appear at larger 2θ angles between 24° and 29°. Fig. 3These are designated λ-ZnPc. The assignment of the reflections was based on the publication by [Schünemann, C. et al.: Evaluation and Control of the Orientation of Small Molecules for Strongly Absorbing Thin Films. The Journal of Physical Chemistry C 2013, 117, 11600-11609]. The reflections designated λ correspond to ZnPc molecules lying flat on the substrate (face-on growth). The calculated distances between parallel crystal planes are in the range of 3.2 Å to 3.7 Å.

[0061] Accordingly, the thin template layer leads to a change in orientation from standing to face-on and to an improvement in the crystallinity of the ZnPc molecules.

[0062] Fig. 4This paper presents the results of GIXRD measurements on donor:C60 mixed layers, with DCV5T-Me2(3,3) as the donor, deposited on 10 nm C60 with and without a template layer. The 30 nm thick mixed layers were deposited on a substrate heated to 80°C, with a mixing ratio of 2:1. The X-ray diffractogram shows the characteristic peaks of the C60 fcc phase for both donor:C60 mixed layers. The donor in the mixed layer, deposited directly onto C60, grows amorphously. In contrast, reflections in the 2θ range between 24° and 30° are observed on the template layer. These are associated with the donor phase in the mixed layer and the template layer. Accordingly, the donor on the template layer grows crystalline. The reflections between 24° and 30° correspond to Bragg distances of 3.7 Å and 3.4 Å.

[0063] These values ​​indicate that the donor molecules are flat-lying (face-on) or at least strongly inclined towards the substrate.

[0064] Fig. 5The measurement results for solar cells containing a photoactive layer of donor:C60 (donor = DCV4T-Et2) are shown. The photoactive layer has a thickness of 30 nm. The photoactive layer was deposited at a substrate temperature of 40°C. The mixing ratio between donor and C60 is 2:1. The gray curve shows the current-voltage characteristic of a device in which the photoactive layer was deposited directly onto C60, and the black curve shows the current-voltage characteristic of a device with the photoactive layer deposited on a 5 nm thick template layer. For the cell with the template layer, the fill factor increases by 13.6% (from 45.2% to 58.8%). This is consistent with the results of the GIXRD measurement ( Fig. 2 This is due to the improved crystallinity of the photoactive layer. The template layer therefore leads to a significantly improved solar cell.

[0065] Fig. 6 This figure shows the measurement results of two solar cells with a photoactive layer of donor:C60 (DCV4T-Et2:C60). The photoactive layer has a thickness of 30 nm. It was deposited at a substrate temperature of 70°C. The gray curve shows the current-voltage characteristic of the device where the donor:C60 layer was deposited directly onto C60, and the black curve shows the current-voltage characteristic of a device with a donor:C60 layer deposited on a 5 nm thick template layer. The fill factor of the solar cell with the template layer is 55.7%, compared to a lower fill factor of 44.9% for the solar cell without the template layer.

[0066] The increase in the fill factor is due to the improved short-range order of the donor phase in the photoactive layer, which grew on the template layer. With the template, Voc also increases, while Jsc decreases slightly. Overall, the template improves cell efficiency: PCE = Voc * jsc * FF.

[0067] Fig. 7This shows the measurement results of two solar cells containing ZnPc:C60 as the photoactive layer. The photoactive layer has a thickness of 30 nm. It was deposited at a substrate temperature of 70°C. The gray curve represents the current-voltage characteristic of the device in which the ZnPc:C60 layer was deposited directly onto C60, whereas the black curve shows the current-voltage characteristic of a device with a ZnPc:C60 layer deposited on a 5 nm thick template layer. The solar cell without a template layer has a fill factor of 36.1%, in contrast to the cell with a template layer, which has a significantly better fill factor of 55.3%. According to the GIXRD data (see Fig. 3 The improved fill factor is due to the crystallinity of the ZnPc phase in the mixed layer caused by the template layer.

[0068] Although Voc and jsc decrease slightly, the overall efficiency PCE = Voc * jsc * FF improves with the template layer.

[0069] In Fig. 8 The measurement results for solar cells containing a photoactive layer of donor:C60 (donor = DCV-TPyTTPyT-Pe2(2,5)) are shown. The photoactive layer has a thickness of 30 nm. The deposition of the photoactive layer took place at a substrate temperature of 70°C. The mixing ratio between donor and C60 is 2:1. The gray curve in Fig. 8Figure 1 shows the current-voltage characteristic of a device in which the photoactive layer was deposited directly onto C60, and the black curve shows the current-voltage characteristic of a device with a photoactive layer deposited on a 2 nm thick template layer. For the cell with the template layer, the fill factor increases from 57.2% to 60.2% compared to the cell without the template layer. This is due to an improved degree of crystallinity of the donor phase in the mixed layer, resulting from the interaction with the crystalline template layer. The overall efficiency PCE = Voc * jsc * FF, however, remains almost unchanged, as the sample with the template layer exhibits a lower current.

[0070] Fig. 9 The results of lifetime measurements of bulk heterojunction solar cells after 800 hours of accelerated aging in an oven at 85°C reveal a surprising finding. The solar cells contain donor:C60 as the photoactive layer. (Donor = DCV-Fu-Py-Fu-V-Me(2)) with a mixing ratio of 2:3. They are fabricated on an ITO-coated glass substrate and have the layer sequence ITO / n-C60 / C60 / template (0 or 2 nm) / donor:C60 (30 nm) / hole conductor / p-doped hole conductor / injection layer / cover electrode (Al). The donor:C60 mixed layer was deposited directly onto the intrinsic C60 layer or onto a template layer.

[0071] For both solar cells, an initial drop in efficiency was observed, after which the solar cells remained stable. The initial drop was most pronounced at 17% for the reference cells without a template layer. In contrast, the drop for the solar cells with a template layer was only 8%. This decrease in efficiency is attributed to the decrease in the fill factor.

[0072] Thus, the measurement results indicate a stabilizing effect of the template layer on the lifetime of the solar cells. One possible explanation is the formation of a more stable fill factor through the preferred molecular orientation achieved with the template material.

Claims

1. Organic optoelectronic component comprising two electrodes and at least one photoactive layer system in between that comprising at least one photoactive layer comprising absorber materials based on small molecules, wherein the absorber material is A-D-A molecules, characterized in that the photoactive layer adjoins a template layer, wherein the template layer comprises a compound of structure (II.1), (II.2), (II.3) and / or (II.4), wherein: Ar1 and Ar2 are two or more bonded aromatic or heteroaromatic rings (Ar1, Ar2), preferably benzene rings, each comprising at least two hydroxyl groups and / or amino groups, R1 to R6 are selected from H, OH, NH2; Y1 is selected from CH, CH2, CO; Y2 is selected from CH, CH2, CO, H; Z1 is selected from CH, CH2, CO, O, NH; Z2 is selected from CH, CH2, CO, O, NH, H; wherein the linkages Y1 ... Z1 and / or Y2 ... Z2 are either covalent or non-covalent, wherein in the first (covalent) case Y1 ... Z1 and / or Y2 ... Z2 may likewise form a substituted aromatic or heteroaromatic mono-, di- or trihydroxy compound.

2. Organic optoelectronic component according to Claim 1, characterized in that the at least one compound of the structure (II.1), (II.2), (II.3) and / or (II.4) is selected from the group consisting of 3. Organic optoelectronic component according to Claim 1 or 2, characterized in that the template layer comprises the at least one compound of the structure (II.1), (II.2), (II.3) and / or (II.4), wherein the template layer is applied before the absorber layer.

4. Organic optoelectronic component according to any of the preceding claims, wherein the organic optoelectronic component is a tandem cell or multiple cell.

5. Organic optoelectronic component according to Claim 4, wherein the organic optoelectronic component comprises various layers having identical or different compounds according to Claim 1 or 2.

6. Organic optoelectronic component according to any of the preceding claims, characterized in that the organic optoelectronic component is an organic solar cell or an organic photodetector, and the template layer comprises ellagic acid.

7. Manufacture of the organic optoelectronic component according to any of the preceding claims, characterized in that during the manufacturing of the layers of the organic optoelectronic component, a) before the applying of at least one absorber layer, the template layer comprising the at least one compound of the structure (II.1), (II.2), (II.3) and / or (II.4) is applied to layers deposited beforehand, and / or b) simultaneously with the absorber materials of the at least one absorber layer, the at least one compound of the structure (II.1), (II.2), (II.3) and / or (II.4) is applied to layers applied beforehand.

8. Use of at least one compound of the structure (II.1), (II.2), (II.3) and / or (II.4) in an organic optoelectronic component comprising at least one photoactive layer that comprises at least one absorber material based on small molecules, wherein the absorber material are A-D-A molecules, wherein the at least one compound of the structure (II.1), (II.2), (II.3) and / or (II.4) adjoins the absorber material, wherein: Ar1 and Ar2 are two or more bonded aromatic or heteroaromatic rings (Ar1, Ar2), preferably benzene rings, each comprising at least two hydroxyl groups and / or amino groups, R1 to R6 are selected from H, OH, NH2; Y1 is selected from CH, CH2, CO; Y2 is selected from CH, CH2, CO, H; Z1 is selected from CH, CH2, CO, O, NH; Z2 is selected from CH, CH2, CO, O, NH, H; wherein the linkages Y1 ... Z1 and / or Y2 ... Z2 are either covalent or non-covalent, wherein in the first (covalent) case Y1 ... Z1 and / or Y2 ... Z2 may likewise form a substituted aromatic or heteroaromatic mono-, di- or trihydroxy compound.

9. Use according to Claim 8, characterized in that the at least one compound of the structure (II.1), (II.2), (II.3) and / or (II.4) is used to improve the morphology of adjacent absorber molecules, wherein the at least one compound is arranged in a template layer in front of the adjacent absorber layer, wherein preferably ellagic acid is used in the template layer.