Organic electronic component with an acceptor layer and a cascade of at least two donor layers which follow each other in direct contact, said cascade being arranged on the acceptor layer

Abstract

The invention relates to an organic electronic component comprising a layer system with a photoactive layer (9). The photoactive layer has an acceptor layer (5) with at least one acceptor and a cascade of at least two donor layers (6, D1, D2, D3) which follow each other in direct contact, said cascade being arranged on the acceptor layer. The invention also relates to the use of a compound of the general formula I and / or a compound of the general formula II in a cascade of an organic electronic component.

Description

[0001] Organic electronic component with an acceptor layer and a cascade of at least two donor layers arranged thereon in direct contact

[0002] The invention relates to an organic electronic component having an acceptor layer and a cascade arranged thereon of at least two donor layers arranged one after the other in direct contact, as well as to a use of a compound of the general formula I and / or a compound of the general formula II in a cascade of an organic electronic component.

[0003] Electronic components with photoactive layers, in particular LEDs or solar cells, are now widely used in everyday and industrial applications. Well-known solar cells preferably have active layers made of amorphous silicon (a-Si) or GIGS (Cu (In, Ga) (S, Se) 2 ). Solar cells with organic photoactive layers are also known. The organic photoactive layers can be made of polymers or small molecules. While polymers are not vaporizable and can therefore only be applied from solutions, small molecules can be vaporized. A solar cell converts light energy into electrical energy. The term photoactive also refers to the conversion of light energy into electrical energy.In contrast to silicon-based solar cells, in organic solar cells, free charge carriers are not directly generated by light. Instead, excitons, i.e. electrically neutral excited states (bound electron-hole pairs), are formed first. Only in a second step are these excitons separated into free charge carriers, which then contribute to the flow of electrical current. The efficiency (power conversion efficiency - PCE) of organic solar cells has been significantly increased in recent years by means of a donor / acceptor interface, bulk heterojunctions, tandem structures, and new materials, particularly new absorbers.

[0004] To improve the efficiency of organic solar cells, both the absorption intensity must be improved and the absorption spectrum broadened. This requires matching absorbers. These absorbers can be combined in cascades within a single cell or in tandem or multiple cells. Excitons formed in one region of the cascade are transferred by Förster energy transfer to a layer of the cascade with a smaller acceptor band gap and then separated into charge carriers at the donor / acceptor interface to the donor layer.

[0005] Cascade-type PHJ cells are known from the prior art. Cascade-type PHJ cells are advantageous over simple PHJ cells because of their greater effectiveness in directing excitation dynamics to an active interface and the coverage of a broad spectral range through the combination of two or more absorbers. However, single PHJs are disadvantageous compared to BHJs in that the efficiency (EQE) is lower. In the cascade, the donor layer of the planar heterojunction is formed from several adjacent donor layers. The transfer of excitons between the donor layer and the acceptor layer at the donor / acceptor interface can occur through Förster resonance energy transfer, with several donor layers contributing to the photocurrent.

[0006] Cnops et al. discloses that organic solar cells with multiple absorbers in cascades of a photoactive layer based on fullerene acceptors do not lead to an improvement in the efficiency of such organic solar cells and therefore proposes the use of fullerene-free acceptors in organic solar cells.

[0007] US10468615B2 discloses organic photovoltaic cells of a heterojunction structure having a first organic donor layer, a first organic acceptor layer, and a second organic acceptor layer on the first organic acceptor layer and / or a second organic donor layer on the first organic donor layer. The optical band gap of the second donor layer is larger than the optical band gap of the first donor layer, the difference being at least 0.1 eV, the difference between the energy level of the HOMO of the first donor layer and the energy level of the HOMO of the second donor layer is not larger than 0.1 eV, and the optical emission spectrum of the second donor layer overlaps with that of the first donor layer.

[0008] However, the efficiency of organic photovoltaic elements must be further increased to make them competitive with conventional silicon-based solar cells. Increasing efficiency requires not only the selection of absorbers (donors and acceptors) and the architecture, such as tandem or triple cells, but also the design of the cell.

[0009] A disadvantage, however, is that planar heterojunctions (PHJs) are not well suited for use in electronic components, especially photovoltaic elements, especially since the efficiency of the photovoltaic elements was severely limited, possibly due to a limited exciton diffusion length in such layers. PHJ cells have therefore not been considered for industrial use in photovoltaic elements to date. The known cascades lead in particular to a loss of the open-circuit voltage V oc .

[0010] It would be desirable to use PHJ cells in photovoltaic elements because they improve the efficiency of photovoltaic elements and simplify production. A PHJ cell, however, has significantly lower process parameter requirements compared to a BHJ cell, since the morphology of individual layers intrinsically has fewer degrees of freedom to control.

[0011] The invention is therefore based on the object of providing an organic electronic component, comprising a layer system with at least one photoactive layer, wherein the at least one photoactive layer is designed as a planar heterojunction (PHJ), with an acceptor layer with at least one acceptor and a cascade arranged thereon of at least two donor layers in direct contact one after the other, wherein the aforementioned disadvantages do not occur, and wherein in particular an improved efficiency of an organic electronic component with such a layer system is provided compared to conventional PHJ cells.

[0012] The problem is solved by the subject matter of the independent claims. Advantageous embodiments emerge from the subclaims.

[0013] The object is achieved in particular by providing an organic electronic component, preferably an organic photovoltaic element, having a first electrode, a second electrode, and a layer system arranged between the first electrode and the second electrode with at least one photoactive layer, wherein the at least one photoactive layer is designed as a planar heterojunction (PHJ), having an acceptor layer with at least one acceptor and a cascade arranged thereon of at least two donor layers in direct contact one after the other, wherein a first donor layer has at least one first donor and a second donor layer has at least one second donor, wherein a donor / acceptor boundary layer is formed between the acceptor layer and the first donor layer, and the at least one acceptor and the at least one first donor form a donor-acceptor system.The first donor layer and the second donor layer differ in that the second donor layer has a larger optical band gap compared to the first donor layer, the optical band gap of the second donor layer being at least 10 meV larger than the optical band gap of the first donor layer. The cascade is preferably designed in such a way that energy transfer in the cascade takes place with essentially low radiation, preferably by means of Förster and / or Dexter transfer. This allows efficient low-radiation transfer of energy in the cascade, with reabsorption or radiation losses being reduced. In the cascade, excitons are transported from a donor layer with a large band gap to a donor layer with a lower band gap and finally dissociated at the donor / acceptor interface to the acceptor layer, so that charges are present.With such an architecture of the layer system, a broad spectrum of light can be covered.

[0014] An optical band gap between two absorbers is understood to mean, in particular, an absorption onset between the two absorbers. An optical band gap difference is understood to mean, in particular, a difference in the absorption onsets.

[0015] In a preferred embodiment of the invention, an electron transport layer (ETL) is arranged between the first electrode and the photoactive layer, in particular the acceptor layer of the photoactive layer, and an HTL hole transport layer (HTL) is arranged between the photoactive layer, in particular the donor layers of the photoactive layer, and the second electrode.

[0016] In a preferred embodiment of the invention, the first donor layer is arranged directly on the second donor layer; particularly preferably, there is no diode semiconductor layer-forming intermediate semiconductor layer, for example a pn-junction, between the first donor layer and the second donor layer.

[0017] A cascade is understood in particular to be a photoactive layer of a PHJ cell with an acceptor layer and a donor layer, wherein the donor layer in turn is formed from at least two donor layers. In contrast to an arrangement of several cells of a photovoltaic element, for example a tandem cell or a triple cell, which can be formed as a cascade, according to the invention a cascade within a photoactive layer is a cell of a photovoltaic element. In the case of several photoactive layers in a cell, several photoactive layers can have such a cascade.

[0018] The term "photoactive" refers, in particular, to the conversion of light energy into electrical energy. Absorber materials in photoactive layers exhibit a large absorption coefficient, at least for a specific wavelength range. Photoactive is preferably understood to mean that absorber materials, in particular at least one donor and / or at least one acceptor, change their charge state and / or polarization state upon exposure to light.

[0019] A photoactive layer is understood in particular to be a layer of an electronic component which contributes to the absorption of radiation and / or to the emission of radiation; in particular, the photoactive layer absorbs radiation.

[0020] In a particularly preferred embodiment of the invention, the first donor layer comprises a compound of the general formula I and / or a compound of the general formula II.

[0021] In a particularly preferred embodiment of the invention, the first donor layer comprises a compound of the general formula IV and / or a compound of the general formula V.

[0022] In a preferred embodiment of the invention, the at least one photoactive layer comprises at least one absorber material. In a particularly preferred embodiment of the invention, the at least one photoactive layer comprises a donor-acceptor system as absorber material, which is designed as a planar heterojunction.

[0023] In a preferred embodiment of the invention, the at least one photoactive layer, in particular the acceptor layer and / or the at least one donor layer, comprises small molecules as absorber material.

[0024] Small molecules are understood to be non-polymeric organic molecules with monodisperse molar masses between 100 and 2000 g / mol that exist in the solid phase under normal pressure (atmospheric pressure) and at room temperature. The small molecules are preferably photoactive.

[0025] The organic electronic component according to the invention has advantages compared to the prior art.

[0026] Advantageously, the efficiency (power conversion efficiency - PCE) of solar cells with PHJ cells can be increased by a donor layer formed in such a cascade.

[0027] Advantageously, the absorption spectrum of such PHJ cells is broadened. The open-circuit voltage Voc is not reduced compared to single PHJ cells. A subcell can cover a wide wavelength range even without donor / acceptor mixtures.

[0028] Advantageously, no donor / acceptor mixtures are required, making the cells easier to fabricate, particularly by evaporation. Advantageously, absorption (exciton harvesting) is increased compared to a single PHJ cell without such a cascade, especially since the exciton transfer is directed between the donor layers, leading to better transfer rates.

[0029] In a preferred embodiment of the invention, the at least one acceptor is an ADA oligomer and / or a fullerene and / or fullerene derivative, preferably selected from the group consisting of: C60, C70, C76, C80, C82, C84, C86, C90 and C94, or a derivative thereof.

[0030] According to a further development of the invention, it is provided that the energy level of the HOMO of the second donor layer corresponds at least largely to the energy level of the HOMO of the first donor layer, preferably in a range of + / - 200 meV, preferably in a range of + / - 100 meV, preferably in a range of + / - 70 meV, preferably in a range of + / - 50 meV, or preferably in a range of + / - 30 meV.

[0031] According to a further development of the invention, it is provided that the at least one first donor absorbs in a spectral range from 600 nm to 800 nm and the at least one second donor absorbs in a spectral range from 580 nm to 780 nm, or the at least one first donor absorbs in a spectral range from 700 nm to 900 nm and the at least one second donor absorbs in a spectral range from 680 nm to 880 nm.

[0032] According to a further development of the invention, it is provided that the acceptor layer and the donor layers each have a layer thickness of 2 to 50 nm, preferably from 5 nm to 30 nm, preferably from 6 nm to 25 nm, preferably from 2 nm to 20 nm, preferably from 4 nm to 20 nm, preferably from 8 nm to 20 nm, preferably from 10 nm to 20 nm, preferably from 2 nm to 15 nm, preferably from 4 nm to 15 nm, or preferably from 10 nm to 15 nm, and / or the cumulative layer thickness of the donor layers is at least 5 nm, preferably at least 8 nm, or preferably at least 10 nm, preferably 5 nm to 25 nm, or preferably 10 to 25 nm.

[0033] In a preferred embodiment of the invention, the first photoactive layer has a layer thickness of 10 nm to 300 nm, preferably from 10 nm to 200 nm, preferably from 10 nm to 150 nm, preferably from 10 nm to 100 nm, preferably from 10 nm to 50 nm, preferably from 20 nm to 200 nm, preferably from 20 nm to 150 nm, preferably from 20 nm to 100 nm, preferably from 20 nm to 50 nm, preferably from 30 to 300 nm, preferably from 30 to 150 nm, or preferably from 30 to 100 nm, preferably from 30 nm to 50 nm, preferably from 50 nm to 200 nm, or preferably from 50 nm to 100 nm.

[0034] In a preferred embodiment of the invention, the first donor layer and the second donor layer have different layer thicknesses. In an alternative embodiment of the invention, the first donor layer and the second donor layer have the same layer thickness.

[0035] According to a further development of the invention, an optical absorption spectrum of the second donor layer overlaps with an optical absorption spectrum of the first donor layer within the visible spectral range in a range of at least 75 meV, preferably at least 100 meV, or preferably at least 200 meV. The overlap of the radiation emitted by the first donor layer with the radiation absorbed by the second donor layer covers a broader spectral range of light. The absorption spectrum of the first donor layer and the second donor layer must not be too far apart to form improved tandem cells and triple cells.

[0036] In a preferred embodiment of the invention, a difference in the onset of absorption of the first donor layer relative to the second donor layer is less than 100 meV, preferably less than 50 meV, or preferably less than 30 meV.

[0037] According to a further development of the invention, it is provided that a difference in the absorption edge between the first donor layer and the second donor layer is less than 100 meV, preferably less than 50 meV, or preferably less than 30 meV. An absorption edge is understood in particular to be a sudden transition from weak to stronger absorption that occurs at a specific point in an electromagnetic spectrum. According to a further development of the invention, it is provided that the at least one first donor and / or the at least one second donor is an ADA oligomer and / or a BODIPY.

[0038] According to a further development of the invention, the first donor is a compound of the general formula IV and the second donor is a compound of the general formula V where L1 is a stronger donor compared to L2 and / or M1 is a stronger acceptor compared to M2, preferably X in the general formula IV is S and X in the general formula V is 0. Such materials enable in particular the construction of PHJ cells that are at least equivalent to BHJ cells.

[0039] In a preferred embodiment of the invention, the first donor layer comprises at least one compound of the general formula IV and / or the general formula V with X being S, and the second donor layer comprises at least one compound of the general formula IV and / or formula V with X being 0.

[0040] According to a further development of the invention, it is provided that the first donor layer and / or the second donor layer of the at least one cascade comprises at least one compound selected from the general compound I and / or the general compound II, with the general formula I:

[0041] where XI and X2 are independently O, S or N-R8 with R8 selected from the group consisting of H, alkyl, aryl, and heteroaryl, RI is a substituted homocyclic 6-membered ring, wherein at least one H atom is substituted by an electron-withdrawing substituent selected from the group consisting of F, Cl, CN, CF3, and COR8 with R8 being Cl-C4-alkyl, or is a substituted or unsubstituted heterocyclic 5-membered ring or 6-membered ring, wherein the heterocyclic 5-membered ring or 6-membered ring has at least one sp2-hybridized N atom with a free electron pair and / or has at least one heteroatom selected from O, S, or N, wherein at least one H atom is substituted by an electron-withdrawing substituent selected from the group consisting of F, Cl, CN, CF3, and COR9 with R9 Cl-C4-alkyl is substituted, R2 and R7 are independently selected from the group consisting of H, halogen, CN, alkyl, fluorinated or partially fluorinated alkyl,unsaturated alkyl, and aryl, R4 and R5 are independently selected from the group consisting of H, halogen, CN, alkyl, fluorinated or partially fluorinated alkyl, unsaturated alkyl, and alkoxy, and R3 and R6 are independently a substituted or unsubstituted homocyclic 6-membered ring or a substituted or unsubstituted heterocyclic 5-membered ring or 6-membered ring; with the general formula II:, II with Yi selected from the group consisting of N and CR21, where R21 is H, alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN, CF3 or SF5, preferably H, C1-C4-alkyl, F or Cl; with Y2 selected from the group consisting of N and CR22, where R22 is H, alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN, CF3 or SF5; with Y3 selected from the group consisting of N and CR23, where R23 is H, alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN, CF3 or SF5, preferably H, C1-C4-alkyl, F or Cl; with Z1 and Z2 independently selected from the group consisting of F, Cl, CN, CF3, C2F5, OCH3, and OC2H5; with RI and R2 independently selected from the group consisting of H, F, Cl, Br, CN, CF3, CHF2, CH2F, Cl-C4-alkyl, O-Cl-C4-alkyl, S-Cl-C4-alkyl, and N-(Cl-C4-alkyl)2, with the proviso that at least RI or R2 is Br, Cl, CN, CF3, CHF2, CH2F, or CH3, preferably Br, Cl or CF3;with R3 and R5 independently of one another selected from the group consisting of H, halogen, CN, unsubstituted and aryl- or heteroaryl-substituted alkyl, unsubstituted and aryl- or heteroaryl-substituted alkenyl, O-alkyl, S-alkyl, an unsubstituted and alkyl-substituted heterocyclic 5-ring and 6-ring, preferably having at least one heteroatom selected from S, O or N, and an unsubstituted and alkyl-substituted homocyclic 6-ring, where the unsubstituted or substituted heterocyclic 5-ring or 6-ring, or the unsubstituted or substituted homocyclic 6-ring may be fused to another unsubstituted or substituted heterocyclic 5-ring or 6-ring;with R4 and R6 independently of one another selected from the group consisting of H, halogen, CN, alkyl, alkenyl, O-alkyl, S-alkyl, a non-substituted and halogen, alkyl, and / or O-alkyl-substituted heterocyclic 5-ring and 6-ring, preferably with at least one heteroatom selected from S, O or N, and a non-substituted and halogen, alkyl, and / or O-alkyl-substituted homocyclic 6-ring; or wherein R3 and R4 and / or R5 and R6 each together form a heterocyclic 5-membered ring or 6-membered ring which is unsubstituted or substituted by halogen, alkyl, O-alkyl, aryl and / or heteroaryl, preferably with at least one heteroatom selected from S, O and N, or a homocyclic 6-membered ring which is unsubstituted or substituted by halogen, alkyl, O-alkyl, aryl and / or heteroaryl. Such materials enable, in particular, the construction of PHJ cells which are at least equivalent to BHJ cells.;

[0042] An organic optoelectronic component is understood in particular to be a photovoltaic element with at least one organic photoactive layer. An organic photovoltaic element makes it possible to convert electromagnetic radiation, particularly in the wavelength range of visible light, into electrical current by utilizing the photoelectric effect. In this sense, the term "photoactive" is understood as the conversion of light energy into electrical energy. In contrast to inorganic solar cells, in organic photovoltaic elements free charge carriers are not directly generated by the light; instead, excitons, i.e. electrically neutral excited states (bound electron-hole pairs), are first formed. Only in a second step are these excitons separated into free charge carriers in a photoactive donor-acceptor transition, which then contribute to the flow of electrical current.

[0043] Substitution is understood in particular to mean the replacement of an H atom by a substituent, in particular all atoms and atom groups except hydrogen. The substituent is in particular selected from the group consisting of a halogen, preferably F, Cl or Br, particularly preferably F, an alkyl group, an alkenyl group, an alkynyl group, an amino group, an alkoxy group, a thioalkoxy group, an aryl group, and a heteroaryl group.

[0044] A heteroatom, in particular a heteroatom in the general formula I and / or the general formula II, is understood to mean in particular an atom selected from the group consisting of O, S or N.

[0045] In a preferred embodiment of the invention, in the general formula I, R3 and / or R6 is a homocyclic 6-membered ring, wherein at least one H atom is substituted by an alkyl group, an alkoxy group and / or an F atom.

[0046] In a preferred embodiment of the invention, in the general formula I, X1 and R6, preferably R8 and R6, and / or X2 and R3, preferably R8 and R3, together form a heterocyclic five-membered ring or six-membered ring with at least one heteroatom selected from the group consisting of S, O and N, or a homocyclic six-membered ring, preferably a heterocyclic 5-membered ring.

[0047] In a preferred embodiment of the invention, in the general formula I, X1 and R7, preferably R8 and R7, and / or X2 and R2, preferably R8 and R2, together form a heterocyclic five-membered ring or six-membered ring with at least one heteroatom selected from the group consisting of O, S and N, or a homocyclic six-membered ring, preferably a heterocyclic 5-membered ring.

[0048] In a preferred embodiment of the invention, in the general formula I, R3 and R6 are independently selected from where * denotes the linkage to the compound of general formula I, Z2 is selected from the group consisting of O, S, and N-R11, where R11 is selected from the group consisting of H, alkoxy, alkyl, fluorinated alkyl, partially fluorinated alkyl, and aryl, Y3 is N or C-R12, where R12 is selected from the group consisting of H, halogen, alkoxy, branched or linear, cyclic or open-chain alkyl, alkenyl, and aryl, where preferably at least one H is substituted, preferably by CN or F, Y4 is N or C-R13, where R13 is selected from the group consisting of H, halogen, alkoxy, branched or linear, cyclic or open-chain alkyl, alkenyl, and aryl, where preferably at least one H is substituted, preferably by CN or F, and wherein preferably R12 and R13 are homocyclic or heterocyclic bonded to each other in the form of a ring structure,and RIO is selected from the group consisting of H, halogen, alkoxy, alkyl, fluorinated alkyl, partially fluorinated alkyl, branched or linear, cyclic or open-chain alkyl, amino, aryl, heteroaryl, alkenyl, and an electron-withdrawing alkyl group having at least one C=C double bond, wherein preferably at least one H is substituted by CN or F.

[0049] In a preferred embodiment of the invention, in the general formula I, the H atoms in Y3 and / or Y4 are at least partially substituted by alkyl, alkoxy or F.

[0050] In a preferred embodiment, in the general formula I, positions Y3 and Y4 are each CH.

[0051] In a particularly preferred embodiment of the invention, in the general formula I RI there is no substituted and / or no unsubstituted thiophene, preferably no unsubstituted thiophene.

[0052] In a particularly preferred embodiment of the invention, in the general formula I, RI is not a substituted and / or unsubstituted furan, preferably not a non-substituted furan. In a particularly preferred embodiment of the invention, in the general formula I, RI is not a substituted and / or unsubstituted pyrrole, preferably not a non-substituted pyrrole.

[0053] According to a further development of the invention, it is provided that in the general compound I, XI and X2 are S or XI and X2 are 0, and / or wherein at least one H atom in the homocyclic 6-membered ring and / or in the heterocyclic 5-membered ring or 6-membered ring RI is substituted by F or CF3, preferably by F; and / or R3 and R4 and / or R5 and R6 each together form a heterocyclic 5-membered ring or 6-membered ring with at least one heteroatom selected from O, S or N, preferably O or S, wherein the heterocyclic 5-membered ring or 6-membered ring is preferably unsubstituted, or form a homocyclic 6-membered ring, and / or RI is a homocyclic 6-membered ring with the condition RI is CgHnFs-n with n=0,1,2,3,4.

[0054] According to a further development of the invention, it is provided that in the general compound II, Z1 and Z2 are F; and / or wherein R1 and R2 are independently selected from the group consisting of H, F, Cl, Br, CN, CF3, Me, Et, OMe, SMe, OEt, SEt, Pr, and iPr, with the proviso that at least R1 or R2 is Br or Cl, wherein preferably R1 and R2 are not H; and / or wherein R1 and R2 are independently selected from the group consisting of Cl, Br, CN, CF3, Me, Et, OMe, SMe, OEt, and SEt, with the proviso that at least R1 or R2 is Cl, Br, CF3 or Me; or wherein R1 and R2 are selected from the group consisting of Br, Cl, CF3, CHF2, and CH2F.

[0055] According to a further development of the invention, it is provided that in the general compound II, Y is selected from the group consisting of N and CR21, where R21 is H or Cl, and / or where Y2 is selected from the group consisting of N and CR22, where R22 is H, CH3, O-CH3, S-CH3, F, Cl, CF3 or SF5, preferably N or CH, and / or where Y3 is selected from the group consisting of N and CR23, where R23 is H or Cl; where preferably one Y2, Y2, Y3 is an N, or two Y2, Y2, Y3 are an N.

[0056] According to a further development of the invention, it is provided that the

[0057] Compound II is the compound of general formula III with Yi selected from the group consisting of N and CR21, where R21 is H, alkyl, preferably Cl-C4-alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN and CF3; with Y2 selected from the group consisting of N and CR22, where R22 is H, alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN or CF3; with Y3 selected from the group consisting of N and CR23, where R23 is H, alkyl, preferably Cl-C4-alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN and CF3; with Z1 and Z2 being F or CF3; with Xi and X2 independently of one another are O, S or N-R8 with R8 is selected from the group consisting of H, alkyl and aryl, preferably Xi and X2 are S or Xi and X2 are O, with R1 and R2 independently of one another are selected from the group consisting of H, F, Cl, Br, CN, CF3, CHF2, CH2F, Cl-C4-alkyl, O-C1-C4-alkyl, S-Cl-C4-alkyl, and N-(Cl-C4-alkyl)2, with the proviso that at least R1 or R2 is Br, Cl, CF3, CH2F, CHF2, or CH3;wherein R13 and R15 are independently selected from the group consisting of H, halogen, CN, alkyl, O-alkyl, and S-alkyl, preferably H or Cl-C4-alkyl, wherein R14 and R16 are independently selected from the group consisting of a heterocyclic 5-membered ring or 6-membered ring which is unsubstituted or substituted by halogen, alkyl, fluorinated alkyl, O-alkyl, and / or fluorinated O-alkyl, preferably having a heteroatom independently selected from S, O and N, and a homocyclic 6-membered ring which is unsubstituted or substituted by halogen, alkyl, fluorinated alkyl, O-alkyl, and / or fluorinated O-alkyl, preferably a non-substituted or substituted heterocyclic 5-membered ring, and a non-substituted or substituted homocyclic 6-membered ring.;

[0058] According to a further development of the invention, it is provided that in the chemical compound of the general formula I Yi and Y3 are CH and Y2 are CR22, preferably with CR22 selected from F, Br, CI, and CN, or Yi are CR21, Y2 are N and Y3 are CR23, preferably with CR21 and CR23 H or methyl, or Yi are N, Y2 are CR22 and Y3 are N, preferably with CR22 H or methyl, where in each case R1 and R2 are preferably F or CI.

[0059] According to a development of the invention, it is provided that the at least one first donor is a compound of the general formula I and / or the general formula II, and the at least one second donor is at least one ADA oligomer and / or a BODIPY, preferably the second donor is a compound of the general formula I and / or a compound of the general formula II, wherein the cascade has a third donor layer which is arranged on the second donor layer, wherein the third donor layer has a band gap which is at least 10 meV larger than that of the second donor layer. In a preferred embodiment of the invention, the third donor layer borders directly on the second donor layer.

[0060] In a preferred embodiment of the invention, the second donor layer has a larger optical band gap compared to the first donor layer, wherein the optical band gap of the second donor layer is at least 15 meV larger compared to the optical band gap of the first donor layer, preferably at least 20 meV, preferably at least 25 meV, preferably at least 25 meV, preferably at least 30 meV, preferably at least 40 meV, preferably at least 50 meV, preferably at least 60 meV, preferably at least 80 meV, preferably at least 100 meV, or preferably at least 200 meV.

[0061] According to a further development of the invention, it is provided that the third donor layer has an optical band gap which is less than 100 meV larger, preferably less than 50 meV, more preferably less than 25 meV, than that of the second donor layer.

[0062] In a preferred embodiment of the invention, in the chemical compound of the general formula I RI is selected from the group consisting of:

[0063] where * denotes the linkage to the compound of general formula I, where Y is independently selected from the group consisting of Cl, CN, F and CF3, preferably Y is F, and where H atoms are substituted or unsubstituted, preferably unsubstituted.

[0064] In a preferred embodiment of the invention, in the chemical compound of general formula I, R3 and R6 are independently selected from the group consisting of

[0065] where * denotes the linkage to the compound of general formula I, where U is selected from the group consisting of O, S and NR19, where R19 is selected from the group consisting of H, halogen, alkyl, fluorinated alkyl, partially fluorinated alkyl, alkoxy, alkenyl, aryl, and heteroaryl, preferably U is O or S, and where Z is independently selected from the group consisting of H, halogen, preferably F, CF3, CN, alkyl, fluorinated alkyl, partially fluorinated alkyl, alkenyl, alkoxy, N-alkyl, NAlkyl2, aryl, and heteroaryl, where preferably R3 and R6 are the same.

[0066] In a preferred embodiment of the invention, in the chemical compound of general formula I, R3 and / or R6 are further annealed, and / or RI is a monocyclic 5-membered ring or 6-membered ring.

[0067] In a preferred embodiment of the invention, in the chemical compound of the general formula I, R2 and R7 are independently selected from the group consisting of H, halogen, CN, and Cl-C4-alkyl, preferably R2 and R7 are H, and / or R4 and R5 are independently selected from the group consisting of H, halogen, CN, and Cl-C4-alkyl, preferably R4 and R5 are H.

[0068] In a preferred embodiment of the invention, in the chemical compound of the general formula I RI is a heterocyclic 5-membered ring or 6-membered ring having at least one sp2-hybridized N atom with a free electron pair in the ring system, preferably RI is selected from the group consisting of substituted or unsubstituted imidazole, pyrazole, triazole, tetrazole, pyridine, pyrimidine, pyrazine, pyridazine, triazine, oxazole, isoxazole, thiazole, and isothiazole.

[0069] In a preferred embodiment of the invention, in the chemical compound of general formula I, the compound is selected from the group consisting of:

[0070] ( 39 ) . PHJ cells with such

[0071] Cascades with compounds according to the invention show a particularly advantageous efficiency, in particular a higher exciton diffusion length, and a better charge separation at the interface to the acceptor layer.

[0072] In a preferred embodiment of the invention, in the chemical compound of the general formula II, R3 and R4 and / or R5 and R6 form a non-substituted or substituted heterocyclic 5-ring or 6-ring with at least one heteroatom selected from O, S and N, preferably from O and S, or a non-substituted or substituted homocyclic 6-ring, or R3 and R4 and / or R5 and R6 form a non-substituted or substituted heterocyclic 5-ring, preferably a substituted heterocyclic 5-ring with at least one heteroatom selected from O, S and N, preferably O and S, or a non-substituted or substituted homocyclic 6-ring, preferably a non-substituted homocyclic 6-ring.

[0073] In a preferred embodiment of the invention, in the chemical compound of the general formula II I, R14 and R16 are independently selected from the group consisting of with X3 is O, S, or N-R9 with R9 selected from the group consisting of H, alkyl and aryl; with R17 to R19 and R31 to R35 independently of one another selected from the group consisting of H, halogen, preferably F and Cl, CN, alkyl, preferably Cl-C4-alkyl, O-alkyl, preferably O-Cl-C4-alkyl, and S-alkyl, preferably S-Cl-C4-alkyl, where preferably at least one H atom in R31 to R35 is substituted by F.

[0074] In a preferred embodiment of the invention, in the chemical compound of the general formula II I, Z1 and Z2 are F, and R1 and R2 are independently selected from the group consisting of H, F, Cl, Br and CF3, with the proviso that at least R1 or R2 is Br, Cl, CF3, CHF2, CH2F or CH3, preferably Br or Cl.

[0075] In a preferred embodiment of the invention, the chemical compound is a compound of the general formula VI

[0076] VI , where Xi and X2 are independently 0 or S, where R 40 H, Ci or F, preferably H, and where Hal is F, Br or Ci. In a particularly preferred embodiment of the invention, the meso substituent on the BODIPY backbone is (4)-3,5-dichloropyridine, i.e. where Hal is each CI, and R40 is H.

[0077] In a preferred embodiment of the invention, the chemical compound is a compound of the general formula VII, vil, where Xi and X2 are independently 0 or S, where R 41 H, F, Cl, Br, CF3 or Cl-C4-alkyl, preferably H or Cl, and wherein Hal is Br, Cl or F.

[0078] In a preferred embodiment of the invention, the chemical compound is a compound of the general formula VII I,

[0079] where Xi and X2 are independently O or S, where R 42H, Cl-C4-alkyl, CI or F, and wherein Hal is Br, CI or F.

[0080] In a preferred embodiment of the invention, the chemical compound of the general formula VI IIR 14 and R 16 a non-substituted or halogen-, alkyl- and / or O-alkyl-substituted heterocyclic 5-membered ring having at least one heteroatom selected from S, O and N, preferably O and S, where preferably R19, R17 and R19, or R18 and R19 are substituted, or a non-substituted or halogen-, alkyl-, fluorinated alkyl-, O-alkyl- and / or fluorinated O-alkyl-substituted homocyclic 6-membered ring, where preferably R32, R33, or R32 and R34 are substituted, or R31 to R35 are H.

[0081] In a preferred embodiment of the invention, the chemical compound of general formula II is selected from the group consisting of:

[0082]

[0083] PHJ cells with such a cascade with compounds according to the invention show a particularly advantageous efficiency, in particular a higher exciton diffusion length, and a better charge separation at the interface to the acceptor layer.

[0084] According to a further development of the invention, it is provided that the layer system is a tandem cell with two cells or a multiple cell with several cells, wherein a conductive intermediate layer is arranged between the cells, and wherein at least one cell, preferably at least two cells, is designed as a cascade according to one of the preceding claims.

[0085] In a preferred embodiment of the invention, at least one donor and the at least one acceptor of the at least one photoactive layer form a donor-acceptor system, wherein the at least one donor is preferably an ADA oligomer and / or a BODIPY, and the at least one acceptor is preferably an ADA oligomer and / or a fullerene or fullerene derivative, wherein preferably the at least one donor and the at least one acceptor are small molecules.

[0086] A BODIPY compound is understood in particular to be a compound of the general formula C9H7BN2F2, i.e. a compound having a boron difluoride group with a dipyrromethene group, in particular a compound 4,4-Dif luoro-4-bora-3a,4a-diaza-s-Indacene.

[0087] An ADA oligomer is understood to mean, in particular, a conj ugated acceptor-donor-acceptor oligomer (ADA ' oligomer ) with an acceptor unit (A) and a further acceptor unit (A ' ), each of which is bound to a donor unit (D).

[0088] In a preferred embodiment of the invention, the first donor layer comprises different donors compared to the second donor layer.

[0089] In a preferred embodiment of the invention, the layer system has at least two, preferably at least three, or preferably at least four photoactive layers, with at least one photoactive layer being designed as a cascade. In a preferred embodiment of the invention, the layer system is designed as a tandem cell, triple cell, or multiple cell.

[0090] According to a further development of the invention, it is provided that the organic electronic component is an organic photovoltaic element (OPV), an OLED (organic light emitting diode), an organic field effect transistor (OFET), or an organic photodetector.

[0091] The object of the present invention is also achieved by providing a use of a compound of the general formula I and / or a compound of the general formula II in a cascade of an organic electronic component, in particular according to one of the previously described embodiments. The use of a compound of the general formula I and / or a compound of the general formula II in a cascade of an organic electronic component results in particular in the advantages that have already been explained in connection with the organic electronic component.

[0092] The invention is explained in more detail with reference to the following exemplary embodiments and figures. In particular, it has been demonstrated in the following exemplary embodiments that an organic electronic component according to the invention with a cascade of donor layers surprisingly exhibits a higher efficiency compared to a corresponding component with only one donor layer. The figures show:

[0093] Fig. 1 is a schematic representation of an embodiment of an organic electronic component in cross section; Fig. 2 is a schematic representation of an embodiment of an organic electronic component with a cascade with two donor layers (Fig. 2A) and a cascade with three donor layers (Fig. 2B), each in cross section;

[0094] Fig. 3 shows, in one embodiment, current-voltage characteristics of an organic electronic component designed as a PHJ cell with an acceptor layer and a donor layer; Fig. 4 shows, in one embodiment, current-voltage characteristics of an organic electronic component designed as a PHJ cell as a cascade with an acceptor layer, a first donor layer, and a second donor layer;

[0095] Fig. 5 shows, in one embodiment, current-voltage characteristics of an organic electronic component as a PHJ cell formed as a cascade with an acceptor layer, a first donor layer, a second donor layer, and a third donor layer; and

[0096] Fig. 6 to Fig. 10 are graphical representations of absorption spectra of different absorbers.

[0097] Examples of implementation

[0098] The compounds Absorberl to AbsorberlO are each absorbers from the class of small molecules:

[0099]

[0100]

[0101] Absorber 10 ( 43 )

[0102] It is shown that an organic photovoltaic element with a cascade according to the invention with two donor layers shows a better efficiency than a single PH J cell with only one donor layer.

[0103] It is further shown that an organic photovoltaic

[0104] Element with an inventive cascade having three donor layers exceeds the efficiency of an inventive cascade having two donor layers.

[0105] Fig . 1 shows a schematic representation of a

[0106] Embodiment of an organic electronic component in cross section.

[0107] The organic electronic component, preferably an organic photovoltaic element, has a first electrode 3, a second electrode 8, and a layer system 1 arranged between the first electrode 3 and the second electrode 8 and having at least one photoactive layer 9, wherein the at least one photoactive layer 9 is designed as a planar heterojunction (PHJ), with an acceptor layer 5 with at least one acceptor and a cascade arranged thereon of at least two donor layers 6 which are in direct contact one after the other, wherein a first donor layer D1 has at least one first donor and a second donor layer D2 has at least one second donor, wherein a donor / acceptor boundary layer is formed between the acceptor layer 5 and the donor layer 6, and the at least one acceptor and the at least one first donor form a donor-acceptor system.The first donor layer Dl and the second donor layer D2 differ in such a way that the second donor layer D2 has a larger optical band gap compared to the first donor layer Dl, wherein the optical band gap of the second donor layer D2 is at least 10 meV larger compared to the optical band gap of the first donor layer Dl.

[0108] The donor layer 6 of the photoactive layer 9, formed as a cascade, enables an improvement in the efficiency of organic photovoltaic elements with such a layer system 1 .

[0109] The donor-acceptor system, in particular the acceptor layer 5 and / or the at least first donor layer D1 6 and second donor layer D2 6 , can be processed in a vacuum, i.e., applied to a layer of the layer system 1 by evaporation in a vacuum. However, the layers can also be deposited by means of vapor deposition or solvent processing.

[0110] In one embodiment of the invention, the energy level of the HOMO of the second donor layer D2 corresponds at least largely to the energy level of the HOMO of the first donor layer D1, preferably in a range of + / - 200 meV, preferably in a range of + / - 100 meV, or preferably in a range of + / - 50 meV.

[0111] In a further embodiment of the invention, the acceptor layer 5 and the donor layers 6 each have a layer thickness of 2 to 50 nm, preferably from 8 nm to 20 nm, and / or the cumulative layer thickness of the donor layers 6 is at least 5 nm.

[0112] In a further embodiment of the invention, an optical absorption spectrum of the second donor layer D2 overlaps with an optical absorption spectrum of the first donor layer D1 within the visible spectral range in a range of at least 75 meV, preferably at least 100 meV.

[0113] In a further embodiment of the invention, a difference in the absorption edge between the first donor layer D1 and the second donor layer D2 is less than 100 meV, preferably less than 50 meV, or preferably less than 30 meV.

[0114] In a further embodiment of the invention, the at least one first donor and / or the at least one second donor is an ADA oligomer and / or a BODIPY.

[0115] In a further embodiment of the invention, the first donor is a compound of the general formula IV and the second donor is a compound of the general formula V

[0116] where LI is a stronger donor compared to L2 and / or Ml is a stronger acceptor compared to M2, preferably X in the general formula IV is S and X in the general formula V is 0.

[0117] In a further embodiment of the invention, the first donor layer D1 and / or the second donor layer D2 of the at least one cascade comprises at least one compound selected from the general compound I and / or the general compound II, with the general formula I: where XI and X2 are independently O, S or N-R8 with R8 selected from the group consisting of H, alkyl, aryl, and heteroaryl, RI is a substituted homocyclic 6-membered ring, wherein at least one H atom is substituted by an electron-withdrawing substituent selected from the group consisting of F, Cl, CN, CF3, and COR8 with R8 being Cl-C4-alkyl, or is a substituted or unsubstituted heterocyclic 5-membered ring or 6-membered ring, wherein the heterocyclic 5-membered ring or 6-membered ring has at least one sp2-hybridized N atom with a free electron pair and / or has at least one heteroatom selected from O, S, or N, wherein at least one H atom is substituted by an electron-withdrawing substituent selected from the group consisting of F, Cl, CN, CF3, and COR9 with R9 Cl-C4-alkyl, R2 and R7 are independently selected from the group consisting of H, halogen, CN, alkyl, fluorinated or partially fluorinated alkyl,unsaturated alkyl, and aryl, R4 and R5 are independently selected from the group consisting of H, halogen, CN, alkyl, fluorinated or partially fluorinated alkyl, unsaturated alkyl, and alkoxy, and R3 and R6 are independently a substituted or unsubstituted homocyclic 6-membered ring or a substituted or unsubstituted heterocyclic 5-membered ring or 6-membered ring; with the general formula II:, with Yi selected from the group consisting of N and CR21, where R21 is H, alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN, CF3 or SF5, preferably H, C1-C4-alkyl, F or Cl; with Y2 selected from the group consisting of N and CR22, where R22 is H, alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN, CF3 or SF5; with Y3 selected from the group consisting of N and CR23, where R23 is H, alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN, CF3 or SF5, preferably H, C1-C4-alkyl, F or Cl; with Z1 and Z2 independently selected from the group consisting of F, Cl, CN, CF3, C2F5, OCH3, and OC2H5; with RI and R2 independently selected from the group consisting of H, F, Cl, Br, CN, CF3, CHF2, CH2F, Cl-C4-alkyl, O-Cl-C4-alkyl, S-Cl-C4-alkyl, and N-(Cl-C4-alkyl)2, with the proviso that at least RI or R2 is Br, Cl, CN, CF3, CHF2, CH2F, or CH3, preferably Br, Cl or CF3;with R3 and R5 independently of one another selected from the group consisting of H, halogen, CN, unsubstituted and aryl or heteroaryl-substituted alkyl, unsubstituted and aryl or heteroaryl-substituted alkenyl, O-alkyl, S-alkyl, an unsubstituted and alkyl-substituted heterocyclic 5-ring and 6-ring, preferably with at least one heteroatom selected from S, O or N, and an unsubstituted and alkyl-substituted homocyclic 6-ring, where the unsubstituted or substituted heterocyclic 5-ring or 6-ring, or the unsubstituted or substituted homocyclic 6-ring can be fused to another unsubstituted or substituted heterocyclic 5-ring or 6-ring;with R4 and R6 independently selected from the group consisting of H, halogen, CN, alkyl, alkenyl, O-alkyl, S-alkyl, a non-substituted and halogen, alkyl and / or O-alkyl substituted heterocyclic 5-ring and 6-ring, preferably with at least one heteroatom selected from S, O or N, and a non-substituted and halogen, alkyl and / or O-alkyl substituted homocyclic 6-ring; or wherein R3 and R4 and / or R5 and R6 each together form a non-substituted or halogen-, alkyl-, O-alkyl-, aryl- and / or heteroaryl-substituted heterocyclic 5-membered ring or 6-membered ring, preferably with at least one heteroatom selected from S, O and N, or a non-substituted or halogen-, alkyl-, O-alkyl-, aryl- and / or heteroaryl-substituted homocyclic 6-membered ring.;

[0118] In a further embodiment of the invention, in the general compound I, XI and X2 are S or XI and X2 are O, and / or at least one H atom in the homocyclic 6-membered ring and / or in the heterocyclic 5-membered ring or 6-membered ring RI is substituted by F or CF3, preferably by F; and / or R3 and R4 and / or R5 and R6 each together form a heterocyclic 5-membered ring or 6-membered ring with at least one heteroatom selected from O, S or N, preferably O or S, where preferably the heterocyclic 5-membered ring or 6-membered ring is not substituted, or a homocyclic 6-membered ring, and / or RI is a homocyclic 6-membered ring with the condition RI is CgHnFs-n with n=0,1,2,3,4.

[0119] In a further embodiment of the invention, in the general compound II, Z1 and Z2 are F; and / or R1 and R2 are independently selected from the group consisting of H, F, Br, Cl, CN, CF3, Me, Et, OMe, SMe, OEt, SEt, Pr, and iPr, with the proviso that at least R1 or R2 is Br or Cl, where preferably R1 and R2 are not H; and / or R1 and R2 are independently selected from the group consisting of Cl, Br, CN, CF3, Me, Et, OMe, SMe, OEt, and SEt, with the proviso that at least R1 or R2 is Cl, Br, CF3 or Me; and / or where R1 and R2 are selected from the group consisting of Br, Cl, CF3, CHF2, and CH2F; and / or Y1 is selected from the group consisting of N and CR21, where R21 is H or Cl, and / or Y2 is selected from the group consisting of N and CR22, where R22 is H, CH3, O-CH3, S-CH3, F, Cl, CF3 or SF5, preferably N or CH, and / or Y3 is selected from the group consisting of N and CR23, where R23 is H or Cl;wherein preferably one Yi, Y2, Y3 is an N, or two Yi, Y2, Y3 are an N;

[0120] In a further embodiment of the invention, the connection

[0121] II the compound of general formula III with Yi selected from the group consisting of N and CR21, where

[0122] R21 H, alkyl, preferably Cl-C4-alkyl, O-alkyl, S-alkyl

[0123] Halogen, preferably F or Cl, CN and CF3; with Y2 selected from the group consisting of N and CR22, where R22 is H, alkyl, preferably Cl-C4-alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN or CF3; with Y3 selected from the group consisting of N and CR23, where R23 is H, alkyl, preferably Cl-C4-alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN and CF3; with Z1 and Z2 being F or CF3; where Xi and X2 are independently O, S or N-R8, where R8 is selected from the group consisting of H, alkyl and aryl, preferably where Xi and X2 are S or Xi and X2 are O, where R1 and R2 are independently selected from the group consisting of H, F, Cl, Br, CN, CF3, CHF2, CH2F, Cl-C4-alkyl, O-Cl-C4-alkyl, S-Cl-C4-alkyl, and N-(Cl-C4-alkyl)2, with the proviso that at least R1 or R2 is Br, Cl, CF3, CHF2, CH2F or CH3; where R13 and R15 are independently selected from the group consisting of H, halogen, CN, alkyl, O-alkyl, and S-alkyl,preferably H or C1-C4-alkyl, where R14 and R16 are independently selected from the group consisting of a non-substituted or halogen, alkyl, fluorinated alkyl, O-alkyl and / or fluorinated O-alkyl substituted heterocyclic 5-membered ring or 6-membered ring, preferably with a heteroatom independently selected from S, O and N, and a non-substituted or halogen, alkyl, fluorinated alkyl, O-alkyl and / or fluorinated O-alkyl substituted homocyclic 6-membered ring, preferably a non-substituted or substituted heterocyclic 5-membered ring, and a non-substituted or substituted homocyclic 6-membered ring, where preferably Y1 and Y3 are CH and Y2 are CR22, preferably where CR22 is selected from F, Br, Cl, and CN, or Y1 and Y3 are CR21, Y2 is N and Y3 is CR23, preferably where CR21 and CR23 are H or Methyl, or Y1 is N, Y2 is CR22 and Y3 is N, preferably with CR22 being H or methyl, where R1 and R2 are each preferably F or Cl.

[0124] In a further embodiment of the invention, the at least one first donor is a compound of the general formula I and / or a compound of the general formula II, and the at least one second donor is at least one ADA oligomer and / or a BODIPY, preferably the second donor is a compound of the general formula I and / or a compound of the general formula II, wherein the cascade has a third donor layer D3 which is arranged on the second donor layer D2, wherein the third donor layer D3 has a band gap which is at least 10 meV larger than that of the second donor layer D2.

[0125] The general preparation of the compounds according to the invention is known to the person skilled in the art. In this context, particular reference is made to international applications WQ2007126052A1 and EP3617214A1.

[0126] In a further embodiment of the invention, the third donor layer D3 has an optical band gap which is less than 100 meV larger, preferably less than 50 meV, more preferably less than 25 meV, than that of the second donor layer D2.

[0127] In a further embodiment of the invention, the layer system is a tandem cell with two cells or a multiple cell with several cells, wherein a conductive intermediate layer is arranged between the cells, and wherein at least one cell, preferably at least two cells, is designed as a cascade according to one of the preceding claims.

[0128] Fig. 2 shows a schematic representation of an embodiment of an organic electronic component with a cascade with two donor layers D1, D2 (Fig. 2A) and a cascade with three donor layers D1, D2, D3 (Fig. 2B), each in cross section. Identical and functionally identical elements are provided with the same reference numerals, so that reference is made to the preceding description.

[0129] In this embodiment, the organic electronic component is an organic photovoltaic element (OPV), but in an alternative embodiment it can also be an OLED, an OFET, or an organic photodetector.

[0130] The layer structure is summarized in Tables 1A and 1B. Table 1A shows the structure of a PHJ cell with a cascade containing a first donor layer D1 and a second donor layer D2 (see (Fig. 2A)). Table 1B shows the structure of a PHJ cell with a cascade containing a first donor layer D1, a second donor layer D2, and a third donor layer D3 (see (Fig. 2B)).

[0131] Table 1A

[0132] ITO: Indium Tin Oxide

[0133] NDP9: commercial p-dopant from Novaled GmbH

[0134] NHT49: commercial hole conductor from Novaled GmbH

[0135] NDN45 : commercial n-dopant of Novaled GmbH

[0136] Table 1B

[0137]

[0138] ITO: Indium Tin Oxide

[0139] NDP9: commercial p-dopant from Novaled GmbH

[0140] NHT49: commercial hole conductor from Novaled GmbH

[0141] NDN45 : commercial n-dopant of Novaled GmbH

[0142] The total layer thickness of the photoactive layers 9 (5 and 6) is always 12 nm in the present embodiments for comparability, but the layer thickness can be adapted according to requirements.

[0143] The layer system 1 is arranged on a transparent substrate 2, which is preferably flexible, in particular as a film. The layer system 1 has a first electrode 3, a second electrode 8, and at least one photoactive layer 9, wherein the at least one photoactive layer 9 is arranged between the first electrode 3 and the second electrode 8. The first electrode 3 is made of transparent indium tin oxide (ITO); alternatively, however, an electrode made of a metal, another conductive oxide, in particular ZnO:Al, or a conductive oxide or polymer, such as PEDOT:PSS or PANI, is also possible. An electron transport layer (ETL) 4 is arranged on the first electrode 3.The photoactive layer 9 is arranged on the electron transport layer 4 and is designed as a planar heterojunction (PHJ) with an acceptor layer 5 and a donor layer 6, wherein the donor layer 6 can consist of several individual donor layers (D1, D2, D3) arranged next to one another. A hole transport layer (HTL) 7, for example made of fullerene C60 or doped fullerene C60, is arranged on the photoactive layer 9. The second electrode 8 is made of a metal, for example Al or Au. In this exemplary embodiment, both the matrix material of the ETL 4 and the acceptor of the acceptor layer 5 are C60.

[0144] The organic materials are printed, glued, coated, vapor-deposited or applied in some other way in the form of thin films or small volumes onto the substrate 2 designed as a film. All processes that are also used for electronics on glass, ceramic or semiconducting substrates can also be used to produce the thin layers. In the present exemplary embodiments, vacuum evaporation of the individual layers of the layer system 1 with the electrodes 3, 8 was used to produce the layer system 1. The materials can be applied by evaporating the corresponding material in a vacuum.

[0145] The layer system 1 formed as a PHJ cell, in this embodiment a single PH J cell, but tandem or triple PH J cells are also possible, with the photoactive layer 9 of an organic electronic component can be produced in one embodiment according to a method comprising the following steps:

[0146] A) Providing a substrate 2 with a first electrode 3 ;

[0147] B ) evaporating an acceptor to apply an acceptor layer 5 by means of vapor deposition;

[0148] C ) evaporating a first donor to apply a first donor layer Dl 6 by means of vapor deposition ;

[0149] C ) evaporating a second donor to apply a second donor layer D2 6 by means of vapor deposition ;

[0150] E ) applying a second electrode 8 ; and

[0151] F) Obtaining the layer system 1 on the substrate 2 with a cascade comprising a first donor layer D1 6 and a second donor layer D2 6 . In vapor deposition, the materials are deposited by evaporation in a vacuum.

[0152] The layer system 1 of the PHJ cell with two donor layers as a cascade in the photoactive layer 9 of an organic electronic component can, in one embodiment, comprise between step C) and step D) as a further step C2) evaporation of a third donor for applying a third donor layer D3 6 by means of vapor phase deposition.

[0153] Fig. 3 shows, in one exemplary embodiment, current-voltage characteristics of an organic electronic component designed as a PHJ cell with an acceptor layer 5 and a donor layer 6. Identical and functionally identical elements are provided with the same reference numerals, so that reference is made to the preceding description.

[0154] In this embodiment, the organic electronic component is an organic photovoltaic element. The structure of the PHJ cell corresponds to that shown in Fig. 2A, based on absorbers 1 to 8 in the donor layer 6.

[0155] The current-voltage characteristics of the organic photovoltaic element of the exemplary embodiments were measured. The cells have the structure of a PHJ cell as shown in Fig. 1. The parameters of the organic photovoltaic element were measured under simulated AMI . 5 illumination (AM = Air Mass; AM = 1.5). In this spectrum, the global radiant power is 1000 W / m 2 (AM = 1.5 as standard value for measuring solar modules). The lamp irradiates the sample in such a way that the second electrode is facing away from the light.

[0156] Table 2 shows the photovoltaic parameters Voc, Jsc and FF parameters of a photovoltaic element of single PH J cells with absorber 1 to absorber 8 in the donor layer 6. Table 2

[0157] The optical properties were determined experimentally. The absorption maxima λmax and the onset of the absorption were determined from 30 nm thick vacuum vapor deposition layers on quartz glass using a photometer. It was also shown that the absorbers 1 to 10 have high thermal stability and can be evaporated in a vacuum without decomposition. Fig. 4 shows an exemplary embodiment of the current-voltage characteristics of an organic electronic component as a PHJ cell designed as a cascade with an acceptor layer i-C60 5, a first donor layer D1 6, and a second donor layer D2 6. Identical and functionally equivalent elements are provided with the same reference numerals, so that reference is made to the preceding description.

[0158] The organic electronic component in this embodiment is an organic photovoltaic element. The current-voltage characteristics of the organic photovoltaic element of the embodiments were measured. The structure of the PHJ cell corresponds to that shown in Fig. 2, based on absorbers 1 to 8 in the first donor layer D1 6 and the second donor layer D2 6 .

[0159] Table 3 shows the photovoltaic parameters Voc , Jsc and FF parameters of a photovoltaic element of PHJ cells with a cascade with a first donor layer Dl 6 and a second D2 6 donor layer.

[0160] Table 3

[0161]

[0162] Using the cascade with Absorber 1 in D1 and Absorber 3 in D2 (Example 7) results in an efficiency of 8.7%, a significant increase compared to the respective single PHJ cells with Absorber 1 at 6.7% and Absorber 3 at 4.0%. The triple cascade with Absorber 1 in D1, Absorber 5 in D2, and Absorber 3 in D3 results in a further increase in efficiency to 9.5%.

[0163] The use of a cascade according to the invention with at least a first donor layer D1 6 and a second donor layer D2 6 leads to a higher efficiency compared to a photovoltaic element with a PHJ with a single acceptor layer 5 and a single donor layer 6, as can be seen in Example 5, whereby the cascade of Absorber2 and Absorber4 is significantly better than just Absorber2 or just Absorber4. Analogously, the cascade from (Example 6) with Absorber1 in D1 and Absorber2 in D2 shows a better efficiency (PCE) than a PHJ single cell with Absorber 1 or Absorber 2. This applies analogously to the cascades of the other examples. Example 10 shows a better efficiency (PCE) than the PHJ single cells with Absorbers9 or Absorber10. The cascades according to the invention also lead to a higher efficiency with long-wavelength absorbers.Such cells with little absorption in the visible spectral range are less efficient as such than the examples with shorter wavelength absorbers (examples 5, 6, 11 etc.), but are attractive both as subcells in multi-cells and for semi-transparent solar cells.

[0164] Fig. 5 shows, in one embodiment, current-voltage characteristics of an organic electronic component as a PHJ cell designed as a cascade with an acceptor layer 5, a first donor layer D1 6, a second donor layer D2 6, and a third donor layer D3 6. Identical and functionally identical elements are provided with the same reference numerals, so that reference is made to the preceding description.

[0165] The organic electronic component in this embodiment is an organic photovoltaic element. The current-voltage characteristics of the organic photovoltaic element of the embodiments were measured. The structure of the PH J cell corresponds to that shown in Fig. 3, based on absorber 1, absorber 6, and absorber 3, and absorber 1, absorber 1, and absorber 4 in the first donor layer D1 6, the second donor layer D2 6, or the third donor layer D3 6.

[0166] Table 4 shows the photovoltaic parameters Voc , Jsc and FF parameters of these PHJ cells with a cascade of the first donor layer Dl 6 , the second donor layer D2 6 , and the third donor layer D3 6 .

[0167] Table 4 The use of the cascade of three donor layers with Absorber1 in D1, Absorber5 in D2 and Absorber3 in D3 (Example 12) leads to an efficiency of 9.5%, which is a significant increase compared to the respective single PH J cells with Absorber1, Absorber5 or Absorber3. However, the cascade of three donor layers with Absorber1 in D1, Absorber5 in D2 and Absorber3 in D3 also leads to a further increase in efficiency compared to the cascades with two donor layers with Absorber1 in D1 and Absorber3 in D2 (Example 7).

[0168] Fig. 6 shows a graphical representation of the absorption spectra of absorbers 2 and 4.

[0169] The absorption spectra with the optical density versus the wavelength of the absorbers were measured for 30 nm thick vacuum-deposited layers on quartz glass, as in the following examples Fig . 7 to Fig . 10 .

[0170] Fig. 7 shows a graphical representation of the absorption spectra of absorber 1 and absorber 4.

[0171] Fig. 8 shows a graphical representation of the absorption spectra of absorbers 1 and 3.

[0172] Fig. 9 shows a graphical representation of the absorption spectra of absorbers 6 and 1 .

[0173] Fig. 10 shows a graphical representation of the absorption spectra of absorbers 1, 5 and 3.

Claims

Patent claims 1. Organic electronic component, preferably an organic photovoltaic element, with a first electrode, a second electrode, and a layer system arranged between the first electrode and the second electrode with at least one photoactive layer, wherein the at least one photoactive layer is designed as a planar heterojunction (PHJ), with an acceptor layer with at least one acceptor and a cascade arranged thereon of at least two donor layers in direct contact, wherein a first donor layer has at least one first donor and a second donor layer has at least one second donor, wherein a donor / acceptor boundary layer is formed between the acceptor layer and the first donor layer, and the at least one acceptor and the at least one first donor form a donor-acceptor system, characterized in thatthat the first donor layer and the second donor layer differ such that the second donor layer has a larger optical band gap compared to the first donor layer, wherein the optical band gap of the second donor layer is at least 10 meV larger compared to the optical band gap of the first donor layer., 2. Organic electronic component according to claim 1, wherein the energy level of the HOMO of the second donor layer corresponds at least largely to the energy level of the HOMO of the first donor layer, preferably in a range of + / - 200 meV, or preferably in a range of + / - 50 meV. 3 . Organic electronic component according to claim 1 or 2 , wherein the at least one first donor absorbs in a spectral range from 600 nm to 800 nm and the at least one second donor absorbs in a spectral range from 580 nm to 780 nm, or the at least one first donor absorbs in a spectral range from 700 nm to 900 nm and the at least one second donor absorbs in a spectral range of 680 nm to 880 nm, and / or the acceptor layer and the donor layers each have a layer thickness of 2 to 50 nm, preferably 8 nm to 20 nm, and / or the cumulative layer thickness of the donor layers is at least 5 nm. 4 . Organic electronic component according to one of the preceding claims, wherein an optical absorption spectrum of the second donor layer overlaps with an optical absorption spectrum of the first donor layer within the visible spectral range in a range of at least 75 meV, preferably at least 100 meV.

5. Organic electronic component according to one of the preceding claims, wherein a difference in the absorption edge between the first donor layer and the second donor layer is less than 100 meV, preferably less than 50 meV.

6. Organic electronic component according to one of the preceding claims, wherein the at least one first donor and / or the at least one second donor is an ADA oligomer and / or a BODIPY.

7. Organic electronic component according to one of the preceding claims, wherein the first donor is a compound of the general formula IV and the second donor is a compound of the general formula V where LI is a stronger donor compared to L2 and / or Ml is a stronger acceptor compared to M2 (as measurable), preferably X in the general formula IV is S and X in the general formula V is 0 . 8 . Organic electronic component according to one of the preceding claims, wherein the first donor layer and / or the second donor layer of the at least one cascade comprises at least one compound selected from the general compound I and / or the general compound II, with the general formula I: where XI and X2 are independently O, S or N-R8 with R8 selected from the group consisting of H, alkyl, aryl, and heteroaryl, RI is a substituted homocyclic 6-membered ring, wherein at least one H atom is substituted by an electron-withdrawing substituent selected from the group consisting of F, Cl, CN, CF3, and COR8 with R8 being Cl-C4-alkyl, or a substituted or unsubstituted heterocyclic 5-membered ring or 6-membered ring, wherein the heterocyclic 5-membered ring or 6-membered ring has at least one sp2-hybridized N atom with a free electron pair and / or at least one heteroatom selected from O, S, or N wherein at least one H atom is substituted by an electron-withdrawing substituent selected from the group consisting of F, Cl, CN, CF3, and COR9 with R9 being Cl-C4-alkyl, R2 and R7 are independently selected from the group consisting of H, halogen, CN, alkyl, fluorinated or partially fluorinated alkyl, unsaturated alkyl, and aryl, R4 and R5 are independently selected from the group consisting of H, halogen, CN, alkyl, fluorinated or partially fluorinated alkyl, unsaturated alkyl, and alkoxy, and R3 and R6 are independently a substituted or unsubstituted homocyclic 6-membered ring or a substituted or unsubstituted heterocyclic 5-membered ring or 6-membered ring; with the general formula II: with Y1 selected from the group consisting of N and CR21, wherein R21 is H, alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN, CF3 or SF5; with Y2 selected from the group consisting of N and CR22, wherein R22 is H, alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN, CF3 or SF5; with Y3 selected from the group consisting of N and CR23, wherein R23 is H, alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN, CF3 or SF5; with Z1 and Z2 independently selected from the group consisting of F, Cl, CN, CF3, C2F5, OCH3, and OC2H5; with RI and R2 independently selected from the group consisting of H, F, Ci, Br, CN, CF3, CHF2, CH2F, Cl-C4-alkyl, O-Cl-C4-alkyl, S-Cl-C4-alkyl, and N-(Cl-C4-alkyl)2, with the proviso that at least RI or R2 is Br, Cl, CN, CF3, CHF2, CH2F, or CH3, preferably Br or Cl;with R3 and R5 independently of one another selected from the group consisting of H, halogen, CN, unsubstituted and aryl or heteroaryl-substituted alkyl, unsubstituted and aryl or heteroaryl-substituted alkenyl, O-alkyl, S-alkyl, a unsubstituted and alkyl-substituted heterocyclic 5-ring and 6-ring, preferably with at least one heteroatom selected from S, O or N, and a unsubstituted and alkyl-substituted homocyclic 6-ring, where the unsubstituted or substituted heterocyclic 5-ring or 6-ring, or the unsubstituted or substituted homocyclic 6-ring can be fused to a further unsubstituted or substituted heterocyclic 5-ring or 6-ring;with R4 and R6 independently selected from the group consisting of H, halogen, CN, alkyl, alkenyl, O-alkyl, S-alkyl, a non-substituted and halogen, alkyl and / or O-alkyl substituted heterocyclic 5-membered ring and 6-membered ring, preferably with at least one heteroatom selected from S, O or N, and a non-substituted and halogen, alkyl and / or O-alkyl substituted homocyclic 6-membered ring; or wherein R3 and R4 and / or R5 and R6 each together form a non-substituted and halogen, alkyl, O-alkyl, aryl and / or heteroaryl-substituted heterocyclic 5-ring or 6-ring, preferably with at least one heteroatom selected from S, O and N, or a non-substituted and halogen, alkyl, O-alkyl, aryl and / or heteroaryl-substituted homocyclic 6-ring.; 9 . Organic electronic component according to one of the preceding claims, wherein in the general compound I XI and X2 are S or XI and X2 are 0, and / or wherein at least one H atom in the homocyclic 6-membered ring and / or in the heterocyclic 5-membered ring or 6-membered ring RI is substituted by F or CF3, preferably by F; and / or R3 and R4 and / or R5 and R6 each together form a heterocyclic 5-membered ring or 6-membered ring with at least one heteroatom selected from O, S or N, preferably O or S, wherein the heterocyclic 5-membered ring or 6-membered ring is preferably unsubstituted, or form a homocyclic 6-membered ring, and / or RI is a homocyclic 6-membered ring with the condition RI is CgHnFs-n with n=0,1,2,3,4.

10. Organic electronic component according to one of the preceding claims, wherein in the general compound II, Z1 and Z2 are F; and / or wherein R1 and R2 are independently selected from the group consisting of H, F, Br, Cl, CN, CF3, Me, Et, OMe, SMe, OEt, SEt, Pr, and iPr, with the proviso that at least R1 or R2 is Br or Cl, wherein preferably R1 and R2 are not H; or wherein R1 and R2 are independently selected from the group consisting of Cl, Br, CF3, CN, Me, Et, OMe, SMe, OEt, and SEt, with the proviso that at least R1 or R2 is Cl, Br, CF3 or Me; or wherein preferably R1 and R2 are selected from the group consisting of Br, Cl, CF3, CHF2, and CH2F; and / or Yi is selected from the group consisting of N and CR21, where R21 is H or Cl, and / or Y2 is selected from the group consisting of N and CR22, where R22 is H, CH3, O-CH3, S-CH3, F, Cl, CF3 or SF5, preferably N or CH, and / or Y3 is selected from the group consisting of N and CR23, where R23 is H or Cl; preferably one Y1, Y2, Y3 is N, or two Y1, Y2, Y3 are N.

11. Organic electronic component according to one of the preceding claims, wherein the compound II is the compound of general formula III with Yi selected from the group consisting of N and CR21, where R21 is H, alkyl, preferably Cl-C4-alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN and CF3; with Y2 selected from the group consisting of N and CR22, where R22 is H, alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN or CF3; with Y3 selected from the group consisting of N and CR23, where R23 is H, alkyl, preferably Cl-C4-alkyl, O-alkyl, S-alkyl, a halogen, preferably F or Cl, CN and CF3; with Z1 and Z2 being F or CF3; with Xi and X2 independently of one another are O, S or N-R8 with R8 selected from the group consisting of H, alkyl and aryl, preferably Xi and X2 are S or Xi and X2 are O, with R1 and R2 independently of one another are selected from the group consisting of H, F, Cl, Br, CN, CF3, CHF2, CH2F, Cl-C4-alkyl, O-Cl-C4-alkyl, S-Cl-C4-alkyl, and N-(Cl-C4-alkyl)2, with the proviso that at least R1 or R2 is Br, Cl, CF3, CHF2, CH2F or CH3;wherein R13 and R15 are independently selected from the group consisting of H, halogen, CN, alkyl, O-alkyl, and S-alkyl, preferably H or Cl-C4-alkyl, wherein R14 and R16 are independently selected from the group consisting of a non-substituted or halogen, alkyl, fluorinated alkyl, O-alkyl, fluorinated O-alkyl substituted heterocyclic 5-membered ring or 6-membered ring, preferably having one heteroatom independently selected from S, O and N, and a non-substituted or halogen, alkyl, fluorinated alkyl, O-; Alkyl, fluorinated O-alkyl substituted homocyclic 6-membered ring, preferably from a non-substituted or substituted heterocyclic 5-membered ring, and a non-substituted or substituted homocyclic 6-membered ring, wherein preferably where Y1 and Y3 are CH and Y2 are CR22, preferably with CR22 selected from F, Br , CI , and CN, or Yi CR21 , Y2 N and Y3 CR23 are, preferably with CR21 and CR23 H or methyl, or Yi N, Y2 CR22 and Y3 are N, preferably with CR22 being H or methyl, where R1 and R2 are each preferably F or Cl.

12. Organic electronic component according to one of the preceding claims, wherein the at least one first donor is a compound of the general formula I, and the at least one second donor is at least one ADA oligomer and / or one BODIPY, preferably the second donor is a compound of the general formula I and / or a compound of the general formula II, wherein the cascade has a third donor layer which is arranged on the second donor layer, wherein the third donor layer has a band gap which is at least 10 meV larger, preferably at least 25 meV larger, compared to the second donor layer.

13. Organic electronic component according to claim 12, wherein the third donor layer has an optical band gap that is less than 100 meV larger, preferably less than 25 meV, than the second donor layer.

14. Organic electronic component according to one of the preceding claims, wherein the layer system is a tandem cell with two cells or a multiple cell with several cells, and wherein at least one cell, preferably at least two cells, is designed as a cascade according to one of the preceding claims. 15 . Use of a compound of general formula I and / or a compound of general formula II in a cascade of an organic electronic component.

Images