EP2671271A1 - Photovoltaic element - Google Patents

Abstract

A photovoltaic element (110) is proposed for conversion of electromagnetic radiation to electrical energy, more particularly a dye solar cell (112). The photovoltaic element (110) has at least one first electrode (116), at least one n-semiconductive metal oxide (120), at least one electromagnetic radiation- absorbing dye (122), at least one solid organic p-semiconductor (126) and at least one second electrode (132). The p-semiconductor (126) comprises silver in oxidized form.

Description

 Photovoltaic element

description

Field of the invention

The invention relates to a photovoltaic element, to a method for producing a solid organic p-type semiconductor for use in an organic component, and to a method for producing a photovoltaic element. Such photovoltaic elements and methods are used to convert electromagnetic radiation, in particular sunlight, into electrical energy; in particular, the invention can be applied to so-called dye-sensitized solar cells. State of the art

The direct conversion of solar energy into electrical energy in solar cells is usually based on the so-called "internal photoelectric effect" of a semiconductor material, ie the generation of electron-hole pairs by absorption of photons and the separation of the negative and positive charge carriers at a pn junction In this way, a photovoltage is generated, which can cause a photocurrent in an external circuit, through which the solar cell gives off its power.As a rule, only those photons, which have an energy, can be absorbed by the semiconductor , which is larger than its band gap, so the size of the semiconductor band gap usually determines the proportion of sunlight, which can be converted into electrical energy.

Solar cells based on crystalline silicon were already produced in the 1950s. The technology was then promoted by application to space satellites. Although silicon-based solar cells are now dominating the earth's market, this technology remains costly. Therefore, attempts are being made to develop new approaches that are more cost-effective. In the following some of these approaches are outlined, which represent the basis of the present invention. An important approach for the development of new solar cells are organic solar cells, ie solar cells, which comprise at least one organic semiconductor material, or solar cells, which comprise other materials instead of solid inorganic semiconductors, in particular organic solids or even liquid electrolytes and semiconductors. So-called dye solar cells are a special case among the innovative solar cells. The Dye Solar Cell (DSC) has hitherto been one of the most efficient alternative solar cell technologies. In a liquid variant of this Efficiencies of up to 11% are currently achieved (see, for example, Grätzel M. et al., J. Photochem., Photobio C, 2003, 4, 145; Chiba et al., Japanese Journal of Appl. Phys. 45, L638-L640). Dye solar cells, of which there are now several variants, usually have two electrodes, of which at least one is transparent. The two electrodes are referred to according to their function as "working electrode" {also "anode", generation of electrons) and "counter electrode" (also called "cathode"). As a rule, an n-conducting metal oxide is applied to the working electrode or in the vicinity of it, in particular as a porous, for example nanoporous, layer, for example a nanoporose layer of titanium dioxide (T1O2) about 10 to 20 μm thick. Furthermore, at least one so-called blocking layer may be provided between the layer of the n-type metal oxide and the working electrode, for example a dense layer of a metal oxide, for example T1O2. The n-type metal oxide is usually mixed with a light-sensitive dye. For example, on the surface of the n-type metal oxide, a monolayer of a light-sensitive dye (for example, a ruthenium complex) may be adsorbed, which can be converted by light absorption in an excited state. On or at the counter electrode is often a few pm thick catalytic layer, such as platinum. The area between the two electrodes is in the conventional dye solar cell usually with a redox electrolyte, such as a solution of iodine () and / or potassium iodide (Kl), filled.

The function of the dye solar cell based on the fact that light is absorbed by the dye. From the excited dye, electrons are transferred to the n-type semiconducting metal oxide semiconductor and migrate therefrom to the anode, whereas the electrolyte provides for charge balance across the cathode. The n-halbieitende metal oxide, the dye and the electrolyte are therefore the essential components of Farbstoffsolarzelie.

However, the liquid electrolyte dye-sensitized cell often suffers from a non-optimal seal, which can lead to stability problems. The liquid redox electrolyte can in particular be replaced by a solid p-type semiconductor. Such solid dye solar cells are also referred to as sDSC (solid DSC). The efficiency of the solid variant of the dye-sensitized solar cell is currently about 4.6-4.7% (Snaith, H., Angew Chem. Int. Ed., 2005, 44, 6413-64 7).

Various inorganic p-type semiconductors such as Cul, CuBr-3 (S (C ₄ Hg) 2) or CuSCN have heretofore been used in solid dye solar lines instead of the redox electrolyte. In this case, for example, findings of photosynthesis can also be used. Also in nature, it is the Cu (I) enzyme plastocyanin, which in the photosystem l the oxidized chlorophyll dimer again reduced. Such p-type semiconductors can be processed by at least three different methods, namely: from a solution, by electrodeposition or by laser deposition. Organic polymers have also been used as solid p-type semiconductors. Examples of these include polypyrrole, poly (3,4-ethylenedioxythiophene), carbazole-based polymers, polyaniline, poly (4-undecyl-2,2'-bithiophene), poly (3-octylthiophene), poly (triphenyldiamine) and poly (N vinylcarbazole). The efficiencies reach up to 2% in the case of poly (N-vinylcarbazole). An in-situ polymerized PEDOT (poly (3,4-ethylenedioxythiophene) has also shown an efficiency of 0.53% The polymers described here are typically not used in their pure form but with additives.

Inorganic-organic mixed systems have also been used instead of the redox electrolyte in dye solar cells. Thus, for example, Cul was used together with PEDOT: PSS as a hole conductor in sDSC (Zhang J. Photochem: Photobio., 2007, 189, 329).

It is also possible to use low molecular weight organic p-type semiconductors, ie non-polymerized, for example monomeric or else oligomeric, organic p-type semiconductors. The first use of a low-molecular-weight p-type semiconductor in solid dye-dye solar cells replaced the liquid electrolyte with a vapor-deposited layer of triphenyiamine (TPD). The use of the organic compound 2,2'7,7'-tetrakis (N, N-di-p-methoxyphenyl-amine) -9,9'-spirobifluorene (spiro-MeOTAD) in dye-sensitized solar cells was reported in 1998. It can be brought in from a solution and has a relatively high glass transition temperature, which prevents unwanted crystallization and poor contact with the dye. The methoxy groups adjust the oxidation potential of the spiro-MeOTAD so that the Ru complex can be efficiently regenerated. Upon insertion of the spiro-MeOTAD alone as a p-conductor, the maximum incident photocon to current conversion efficiency (IPCE) was 5%. When N (PhBr) ₃ SbC! ₆ (as dopant) and Li [(CF ₃ S0 ₂ ) ₂ N], the IPCE increased to 33% and the efficiency was 0.74%. By using tert-butylpyridine as a solid p-type semiconductor, the efficiency could be increased to 2.56%, with the voltage at open circuit (V _oc ) about 910 mV and the short-circuit current Isc about 5 mA at a active area of about 1.07 cm ² (see Krüger et al., Appl. Phys. Lett., 2001, 79, 2085). Dyes which have better coverage of the TiO ₂ layer and which have good wetting on spiro-MeOTAD show efficiencies of over 4%. Even better efficiencies (about 4.6%) were reported when the ruthenium complex was equipped with oxyethylene side chains. In Schmidt, Mende et al., Adv. Mater. 17, p. 813-815 (2005), an indoline dye is proposed for dye-containing solar cells with spirobifluorenes as the amorphous organic p-conductor. beat. This organic dye, which has a four-fold higher extinction coefficient than a ruthenium complex, shows high efficiency (4.1% for a sun) in solid dye-sensitizer cells. Furthermore, a concept was presented in which polymeric p-type semiconductors are bonded directly to a Ru dye (Peter, K., Appl., Phys. A 2004, 79, 65). In Durrant et al., Adv. Unc. Mater. 2006, 16, 1832-1838, it is described that in many cases the photocurrent is directly dependent on the yield at the hole transition from the oxidized dye to the solid p-conductor. This depends on two factors: first, the extent of penetration of the p-semiconductor into the oxide pores, and second, the thermodynamic driving force for the charge transfer (ie in particular the difference in free enthalpy between the dye and the p-conductor).

A disadvantage of the dye-like solar cell is that the amount of light that can be used by the dye is usually limited by the energetic distance between the Fermi energies of the n- and p-type conductors used. The photovoltage is usually limited by this distance. In addition, dye solar cells usually have to be made comparatively thin due to the required charge transport (for example 1 to 2.5 micrometers), so that the utilization of the incident light is generally not optimal.

It is known from the prior art that the incorporation of silver nitrate (AgNC) into the dye solution can lead to an increase in the solar cell efficiency (J. Krueger, Dissertation, EPFL Lausanne, 2003 (Thesis No. 2793), p. 76- 100). The general use of silver in oxidized form as a dopant for the p-type semiconductor is not described.

The electrical and photoelectric properties of dye-sensitized solar cells with various low-molecular-weight p-type semiconductors have been investigated in various other works. An example of this can be found in U. Bach, Dissertation, EPFL Lausanne, 2000 (Thesis N ° 2187), in particular on pages 139-149. Here, among other things, the conductivity of spiro-MeOTAD was examined, which is very low. Thus, in films with a layer thickness of about 2 micrometers resistances of Ω / cm ^{2 were} measured. The conductivity κ is defined by = p N _h e (1).

Here, e = 1.6022 × 10 ⁹ C denotes the elementary charge of an electron or hole, μ denotes the charge carrier mobility, and N denotes the charge density, in this case the holes. Assuming that the mobility does not change, the conductivity of a p-type material increases with the addition of additional holes, ie with p-doping. This leads to the fact that the filling factors of sDSCs, especially at low light intensity are not very high. The fill factor in photovoltaics is usually the quotient of the maximum power of a solar cell at the point of maximum power and the product of the open circuit voltage and the short-circuit current. In the current-voltage diagram, the filling factor can often be described as the area ratio of a maximum rectangle inscribed under the current-voltage curve to a minimal rectangle enclosing the curve. The fill factor is unitless. A low fill factor usually indicates that some of the power generated is lost at the line's internal resistance. In the case of Spiro-eOTAD described above, the comparatively low filling factors can therefore be explained in particular by the high specific resistance of the spiro-MeOTAD, as also described, for example, in F, Fabregat-Santiago et al., J. Am. Chem. Soc., 2009, 131 (2), 558-562, especially at 1 sun light.

It is also known from the prior art to dope low molecular weight organic p-type semiconductors. For example, in U. Bach, Dissertation, EPFL Lausanne, 2000 (Thesis N ° 2187), pp. 37-50, antimony salts were used as dopants for spiro-MeOTAD. The process of doping can be chemically described as follows: [N (^ - C ₆ H ₄ Br) _3] ⁺ [SbCl _6] - + spiro MeOTAD

-> [N (yoC ₆ H ₄ Br) ₃ ] + [SbCl ₆ ] - + Spiro-MeOTAD *

In this case, a concentration of 0.26-0.33mM Sb was used, with a share of 0.17-0.18 M in spiro compounds. However, as the conductivity increases, hole mobility diminished by the addition of the anions which degrade charge transport. In addition, the stability of such antimony salts in the cells was questioned.

Also in N. Rossier-Iten, Dissertation, EPFL Lausanne, 2006 (Thesis N ° 3457), in particular pp. 56-75 and pp. 91-113 various doped hole conductor materials were investigated. Among others, 12, 2 _J 3-dichloro-5,6-dicyano-1,4-benzoquinone, NOBF4 and also a doped spirodiradicalcation (spiro-MeOTAD ⁺⁺ [PF ₆ ] 2) were used as dopant of an amorphous hole conductor in sDSCs ( 0.1-0.7%). However, a significant improvement in sDSC cells was not achieved.

In Snaith et al., App !. Phys. Lett. 2006, 89, 2621 14-262116 it has been found that the mobility of holes in sDSCs is greatly enhanced by the addition of lithium bis (trifluoromethy [-sulfonyl) amine (Li-TFSI). Thus, the mobilities could be increased from 1.6 x 10 ^-4 cm ² / Vs to 1.6 x 10 ³ cmWs, although no oxidation of spiro-MeOTAD is observed, ie no actual doping effect. It has been found that the conductivity of Spiro-MeOTAD is less affected by the antimony salt and that the best sDSC cells can be achieved even without such a salt since the anions act as so-called Coulomb traps.

Typically, an amount of dopant greater than 1 mole% is needed to enhance the charge mobility of an amorphous p-type conductor.

Also, organic p-type dopants such as F4-TCNQ (tetrafluoro-tetracyanoquinodimethanes) have been used with p-type organic polymers (see, eg, R. Friend et al, Adv. Mater., 2008, 20, 3319-3324, Zhang et ai, Adv.Funct., Mater., 2009, 19, 1901-1905). A so-called protonic doping of polythiophene by alkylsilanes has also been reported (see Podzorov et al., Advanced Functional Materials 2009, 19, 1906-191 1). However, devices with organic dopants have in many cases comparatively short lifetimes. Furthermore, it is known that also SnCIs and FeC can be used as p-dopants. In addition, polymers such as PEDOT doped with UCF3SO3, L1BF4, LiTFSI and LiCi0 _{4 have also been used} as holey titers in sDSCs. Even with such devices, however, comparatively low external power efficiencies of up to 2.85% were recorded (Yanagida et al., JACS, 2008, 130, 1258-1263).

Furthermore, the use of metal oxides as dopants is also known from the prior art, for example from DE 10 2007 024 153 A1 or from DE 10 2007 023 876 A. Metaxoxides are vapor-deposited in organic layers and serve there as dopants. As an example phenantroline derivatives are called as complex-forming matrix mate- rial, which are doped, for example, with rhenium oxides.

Furthermore, work is also known for doping organic p-transport materials for organic light-emitting diodes by means of vapor-deposited inorganic compounds, for example from Kim et al., Appl. Phys. Lett. 2007, 91, 0111 13 (1-3). For example, NPB was doped with Re03 (8-25%), resulting in lower turn on voltages and higher power efficiencies. The stability of the OLEDs has also been improved. In Kim et al., Org. Elec. 2008, 805-808 describes that hole injection layers were doped with Cul. This doping also led to higher current efficiencies and quantum efficiencies. In Kim et al., Appl. Phys. Lett. 2009, 94, 123306 (1-3) compare Cul, M0O3 and Re0 ₃ as dopants for organic light-emitting diodes (OLEDs). A trend is observed in that the energy difference between the HOMO (highest occupied molecular orbital) of the organic p-type semiconductor and the Fermi level of the dopants plays an important role. Overall, it was found that the dopants increase the carrier densities and thus the conductivities in the transport layers, which is equivalent to a p-type doping. From Kahn et al., Chem. Mater. 2010, 22, 524-531 it is known that molybdenum dithioline (Mo (tfd) 3) in a concentration of 0-3.8 mol% can dope different Lochieiter. In the middle of UPS experiments (UV photoelectron spectroscopy) it was shown that the Fermi level of the hole conductor was shifted in the direction of the HOMO, which is an indication of a p-type doping.

In Kowalsky et al., Org. Elec. 2009, 10, 932-938, reports that Mo30g ~ clusters of evaporated M0O3 are likely to be formed, and may play a role in doping. Furthermore, it was measured that the Femi level (6.86 eV) and the electron affinity (6.7 eV) are much lower than previously assumed. It has also been speculated (see Kanai et al., Organic Electronics 2010, 11, 188-194) that M0O ₃ layers can be slightly n-doped by oxygen vacancies, resulting in improved band alignment (band alignment). leads.

The use of pure layers of metal oxides, such as M0O3 and V2O5, is also described for OLEDs as well as for organic solar cells in order to improve the hole injection or hole extraction from / into the electrode. For example, in Y. Yang et al., Appl. Phys. Lett. 2006, 88, 073508 investigated the use of V ₂ O ₅ , M0O ₃ and PEDOT: PSS as an intermediate layer between ITO (indium tin oxide) and a p-type polymer. Also in so-called inverted polymer cells, in which holes from the p-type polymer in the cathode (in this case, usually Ag) to migrate, a VOx layer was vapor-deposited between the polymer and the silver, resulting in an improvement of the properties led the cell.

Furthermore, the production of metal oxide buffer layers from an aqueous solution is also known. For example, in Liu SEMSC, 2010, 842-845, vol. 94 described that MoO 3 layers were successfully used as a buffer layer on the anode in polymer solar cells. Such layers have also been used as part of a charge recombination layer in so-called organic tandem solar cells (see, for example, Kowalsky et al., Adv. Func. Mater., 2010, 20, 1762-1766).

Since generally no efficient, soluble and stable p-type dopant for hole transport materials is known, dye solar cells have in many cases been stored in air (environmental conditions) in recent years. The sDSC is doped by oxygen entering the sDSCs. The storage of cells in an ambient atmosphere or in a controlled 02 atmosphere, however, is less reproducible and rather problematic in terms of commercial production of solar modules. Furthermore, it is impossible to air-tightly encapsulate cells doped with oxygen, since a high conductivity of the hole conductor necessary for the operation is ensured only under constant contact with oxygen. Object of the invention

It is therefore an object of the present invention to provide a photovoltaic element as well as a method for producing a photovoltaic element, which at least largely avoid the disadvantages of known photovoltaic elements and manufacturing processes, in particular, a photovoltaic element are to be given, which with a p-type semiconductor has a high conductivity, as well as a method for doping p-type semiconductor and a stable p-type dopant, which causes a stable p-type doping of organic materials for dye-sensitized solar cells even in the absence of oxygen. In this case, a dye solar cell which is stable even in an encapsulated state and which has a high quantum efficiency and a high fill factor would nevertheless be desirable, which is nevertheless easy to produce. Disclosure of the invention

This object is achieved by the invention with the features of the independent claims. Advantageous developments, which can be implemented individually or in any combination, are shown in the dependent claims.

In a first aspect of the present invention, a photovoltaic element for converting electromagnetic radiation into electrical energy is proposed, in particular a dye-sensitized solar cell. The photovoltaic element comprises at least one first electrode, at least one n-type semiconducting metal oxide, at least one electromagnetic radiation absorbing dye, at least one solid organic p-type semiconductor and at least one second electrode, preferably (but not necessarily) in the illustrated order or one reverse order, wherein the p-type semiconductor has silver in oxidized form. The p-type semiconductor may in particular be preparable or produced by applying at least one p-type organic material (128) and silver in oxidized form to at least one support element, the silver in oxidized form preferably being in the form of at least one silver (I). Salt [Ag ⁺ ] _m [A ^m ] is applied to at least one support element, wherein A ^m - is the anion of an organic or inorganic acid, and m is an integer in the range of 1 to 3, preferably wherein m is 1.

[A ^m -] may in particular be an anion of an organic acid, preferably wherein the organic acid has at least one fluoro group -F or cyano group (-CN). Here, [A ^m ] particularly preferably has a structure of the formula (II)

O

R ^a SX

O (II) wherein R ^{a is} a fluoro group -F or a, at least with a fluoro group or cyano group (-CN) substituted alkyl radical, cycloalkyl radical, aryl radical or heteroaryl radical, and wherein X is -O- or -N ^" -R ^b , and wherein R ^b a fluoro group -F or a cyano group and wherein R ^b further comprises a group of the formula -S (0) ₂ -.

In particular, R ^a may be selected from the group consisting of -F, -CF ₃ , -CF ₂ -CF ₃ and -CH ₂ -CN.

X may in particular be ^" -R ^b , and R ^b may in particular be selected from the group consisting of -S (O) 2-F, -S (O) ₂ -CF ₃ , -S (O) ₂ -CF ₂ -CF ₃ and -S (0) ₂ -CH ₂ -CN.

[A ^m ] may in particular be selected from the group consisting of:

Bis (trifluoromethylsulfonyl) imide (TFSI), bis-trifluoroethylsulfony imide, bis (fluorosulfonyl) imide, trifluoromethyl sulfonate.

Preferably, [A ™ -] bis (trifluoromethylsulfonyl) imide (TFSI).

According to an alternative preferred embodiment, [A ^m -] is a trifluoroacetate group.

Furthermore, [A ^m ] may in particular also be a NO 3 ^" group.

The application can be done by any method. The application of the at least one organic material (128) and of silver in the context of the invention preferably takes place by deposition from a liquid phase.

The p-type semiconductor is preferably preparable or produced by applying at least one p-type organic material (128) and at least silver, preferably of the at least one silver (l) salt [Ag ⁺ ] _m [A ^m -], to at least one carrier element, the deposition being effected by deposition from a liquid phase comprising the at least one aligning organic material and the at least one silver (I) -Safz [Ag ⁺ ] _m [A ^m -].

The deposition can in turn be carried out in principle by any deposition process, for example by spin coating, doctor blading, printing or combinations of said and / or other deposition methods. The p-type semiconductor may in particular comprise at least one organic matrix material, wherein the anionic compound [A ^m -] and Ag ^{+ are} mixed into the matrix material or contained in the matrix material, in particular dissolved.

At least Ag ⁺ and preferably also the anionic compound [A ^m -] may be distributed substantially evenly, in particular in the matrix material.

The matrix material may in particular comprise at least one low molecular weight organic p-type semiconductor.

The low molecular weight organic p-type semiconductor may in particular comprise at least one spiro compound.

The low molecular weight organic p-type semiconductor may in particular be selected from: a spiro compound, in particular spiro-MeOTAD; a compound with the structural formula:

in which

A, A ² , A ³ , independently of one another, are optionally substituted, aryl groups or heteroaryl groups, R ¹ , R ² , R ^{3 are} independently selected from the group consisting of the substituents -R, -OR, -NR ₂ , -A ⁴ -OR and -A -NR ₂ , wherein R is selected from the group consisting of Alkyl, aryl and heteroryl, and wherein A ^{4 is} an aryl group or heteroaryl group, and wherein n is independently 0, 1, 2 or 3 for each occurrence in formula I, with the proviso that the sum of the individual values n is at least 2 and at least two of the radicals R ¹ , R ² and R ^{3 are} -OR and / or -NR ₂ . Preferably, A ² and A ^{3 are the} same, therefore the compound of formula (I) preferably has the following structure (Ia)

The photovoltaic element may further comprise at least one encapsulation, wherein the encapsulation is arranged to shield the photovoltaic element, in particular the electrodes and / or the p-type semiconductor, from an ambient atmosphere.

According to a preferred embodiment, the p-type semiconductor is prepared or producible by applying at least one p-type organic material (128) and at least one silver (I) salt [Ag ⁺ ] _m [A ^m -] on at least one support element as described above, wherein the deposition by deposition from a liquid phase, the at least one p-type organic material and the at least one Silver (l) salt [Ag ⁺ ] m [A ^m -], and wherein the liquid phase contains at least one silver (l) -Sa! Z [Ag ⁺ ] _m [A ^m -] in a concentration of 0.5 mM / ml to 50 mM / ml, more preferably in a concentration of 1 mM / ml up to 20 mM / ml.

In a further aspect of the present invention, a method is proposed for producing a solid organic p-type semiconductor for use in an organic component, in particular a photovoltaic element according to one or more of the above-described or yet to be described embodiments of a photovoltaic element according to the present invention. In the method, at least one p-type organic matrix material and at least silver in oxiderter form, preferably at least one of silver (l) salt, [Ag ^+] m [A ^m i, is applied at least egg ner liquid phase at least one support element, wherein [A] - is the anion of an organic or inorganic acid, and wherein the compound [Ag ⁺ ] _m ] A ^m -] is preferably AgNC> 3 or silver bts- (trifluoromethylsulfonyI) imide.

The liquid phase may further comprise at least one solvent, in particular an organic solvent, in particular a solvent selected from the group consisting of cyclohexanone; Chlorobenzene; Benzofuran and cyclopentanone.

In particular, the method can be carried out at least partially in an oxygen-poor atmosphere, for example an atmosphere containing less than 500 ppm oxygen, in particular less than 100 ppm oxygen and more preferably less than 50 ppm or even less than 10 ppm oxygen.

In a further aspect of the present invention, a method is proposed for producing a photovoltaic element, in particular a photovoltaic element according to one or more of the above-described or yet to be described embodiments of a photovoltaic element according to the present invention. In the method, at least one first electrode, at least one n-type semiconducting metal oxide, at least one electromagnetic radiation absorbing dye, at least one solid organic p-type semiconductor and at least one second electrode will be provided, particularly (but not necessarily) in the order shown or a reverse order, wherein the p-type semiconductor is produced by a method according to one or more of the above-described or to be described embodiments of a method according to the invention for producing a solid organic p-type semiconductor. Surprisingly, it has been found in the context of the present invention that silver in oxidized form can be used to achieve efficient p-doping, in particular in dye-dye cells. A particularly efficient p-doping can be achieved in particular by the use of a silver (I) salt of the formula [Ag ⁺ ] _m [A ^m -], where [A ^m ] is the anion of an organic or inorganic acid, and m is an integer in the range of 1 to 3. These silver (I) salts can be applied in particular in a liquid phase by means of one or more organic solvents, preferably together with a p-semiconducting matrix material and optionally one or more organic salts. In this way, photovoltaic elements with high filling factors and a high long-term stability can be achieved.

In the above-mentioned first aspect of the present invention, therefore, a photovoltaic element for converting electromagnetic radiation into electrical energy is proposed. The photovoltaic element may in particular comprise one or more photovoltaic cells. The photovoltaic element may in particular comprise at least one layer structure, which may be applied, for example, to a substrate. The photovoltaic element may in particular comprise at least one dye solar cell and / or be designed as a dye solar cell. The photovoltaic element has at least one first electrode, at least one n-semiconducting metal oxide, at least one dye which absorbs electromagnetic radiation, at least one solid organic p-type semiconductor and at least one second electrode. It is proposed that the p-type semiconductor contains silver in oxidized form.

The illustrated elements may be provided in particular in the sequence shown. For example, in the order shown, the photovoltaic element may comprise the at least one first electrode, the at least one n-type semiconducting metal oxide, the at least one electromagnetic radiation absorbing dye, the at least one solid organic p-type semiconductor and the at least one second electrode. However, the dye and the n-semiconducting metal oxide may also be combined in whole or in part, as is usual in dye-sensitized solar cells. For example, the n-type semiconducting metal oxide may be wholly or partially impregnated with the at least one dye or otherwise mixed with this dye. In this way and / or in another way, the n-semiconducting metal oxide can be sensitized in particular with the dye, so that, for example, dye molecules can be applied as a monolayer to particles of the n-semiconducting metal oxide. For example, there may be a direct contact between the dye molecules and the n-semiconducting metal oxide, so that a transfer of charge carriers is possible. The photovoltaic element may in particular at least one layer of the n-semiconducting metal oxide, optionally with the dye, as well as at least one layer of solid organic p-type semiconductor. This layer structure can be embedded between the electrodes. In addition, the photovoltaic element may comprise one or more further layers. For example, one or more further layers can be introduced between the first electrode and the n-semiconducting metal oxide, for example one or more buffer layers, for example layers of a metal oxide. While the buffer layer is preferably designed to be dense, the n-semiconducting metal oxide may in particular be made porous and / or particulate. In particular, the n-semiconducting metal oxide, as will be described in more detail below, can be configured as a nanoparticulate layer. Furthermore, one or more further layers may also be provided between the n-semiconducting metal oxide and the solid organic p-semiconductor, as well as optionally one or more further layers may be provided between the p-semiconductor and the second electrode. The p-type semiconductor may in particular be p-doped by the silver in oxidized form, preferably by the at least one silver (I) salt of the formula [Ag ⁺ ] _m [A ^m ]. This means that the p-type properties of the p-type semiconductor are generated or amplified by the silver in oxidized form, preferably by the at least one silver (I) salt of the formula [Ag ⁺ ] _m [A ^m -]. In particular, the silver in oxidized form, in particular the at least one silver (I) salt of the formula [Ag ⁺ ] _m [A ^m ], can be designed to dope the p-type semiconductor or a matrix material contained in this p-type semiconductor. For example, the p-type semiconductor may comprise at least one organic matrix material, wherein the silver in oxidized form, preferably the at least one silver (I) salt of the formula [Ag ⁺ ] _m [A ^m -], is mixed into the matrix material. This is preferably achieved in that both silver in oxidized form, preferably at least one silver (I) salt of the formula [Ag ⁺ ] _m [A ^m ], and the organic matrix material! be applied to at least one carrier material.

Accordingly, the present invention preferably relates to a photovoltaic element as described above, wherein the p-type semiconductor is producible or manufactured by applying at least one p-type organic material (128) and silver in oxidized form to at least one support element the silver in oxidized form is preferably applied in the form of at least one silver (I) salt [Ag ⁺ ] _m [A ^m -] on at least one support element, where A ^{m ~ is} the anion of an organic or inorganic acid, and m is an integer is in the range of 1 to 3, preferably where m is 1.

In this case, the matrix material and the silver can be applied together or in separate steps on the Trägermatreial. Preferably, the matrix material and the silver are applied together on the carrier material. In this context, "co-applied" or "co-applied" means that preferably a mixture G comprising both the matrix material is applied to the carrier material in at least one step, preferably in one step. Preferably, mixture G is a liquid phase. The term "liquid phase" in this context means that mixture G is present at least partly as a liquid Preferably, mixture G or preferably the liquid phase comprises at least one solvent in which silver and the at least one organic matrix material are dissolved and / or dispersed As described above, the application is preferably carried out by deposition from the liquid phase, the deposition in turn may in principle be carried out by any deposition process, for example by spin coating, knife coating, printing or combinations of the above and / or others deposition.

The low-molecular-weight organic p-type nitrile: The matrix material may in particular have at least one low molecular weight organic p-type semiconductor. In this case, a low-molecular-weight material is generally understood as meaning a material which is present in monomeric, non-polymerized or non-oligomerized form. Preferably, the term "low molecular weight" as used herein means that the semiconductor has molecular weights in the range of 100 to 25,000 g / mol Preferably, the low molecular weight substances have molecular weights of 500 to 2000 g / mol These low molecular weight organic p-type semiconductors In the context of the present invention, p-semiconducting properties are understood to be the property of materials, in particular organic molecules, to form holes and to transport these holes In particular, a stable oxidation of these molecules should be possible Furthermore, said low molecular weight organic p-type semiconductors may in particular comprise an extended π-electron system In particular, the at least one low-molecular-weight p-type semiconductor may consist of a sol be processible. The low molecular weight p-type semiconductor may in particular comprise at least one triphenylamine. It is particularly preferred if the low molecular weight organic p-type semiconductor comprises at least one spiro compound. A spiro compound is to be understood as meaning polycyclic organic compounds whose rings are connected to only one atom, which is also referred to as spiro atom. In particular, the spiro atom can be sp ³ -hybridized, so that the components of the spiro compound that are in communication with one another via the spiro atom are arranged, for example, in different planes relative to one another. Most preferably, the spiro compound has a structure of the following formula: where the radicals aryl, aryl ² , aryl ³ , aryl ⁴ , ary! ⁵ , aryl ⁶ , aryl ⁷ and aryl ^{8 are} independently selected from substituted aryl radicals and heteroaryl radicals, in particular from substituted phenyl radicals, where the aryl radicals and heteroaryl radicals, preferably the phenyl radicals, independently of one another, are preferably each selected with one or more substituents from the group consisting of -O-alkyl, -OH, -F, -Cl, -Br and -I, wherein alkyl is preferably methyl, ethyl, propyl or isopropyl. Particularly preferably, the phenyl radicals, independently of one another, are each substituted by one or more substituents selected from the group consisting of -O-Me, -OH, -F, -Cl, -Br and -I.

More preferably, the spiro compound is a compound of the following formula:

wherein R ^r , R ^s , R ^l , R ^u , R, R ^w , R ^x and R v are independently selected from the group consisting of -O-alkyl, -OH, -F, -Cl, -Br and -I where alkyl is preferably methyl, ethyl, propyl or isopropyl. Particularly preferred are R ^r , R ^s , R ', R ^u , R ^v , R ^w , R ^x and R ^y , independently selected from the group consisting of -O-Me, -OH, -F, - Cl, -Br and -I.

In particular, the p-type semiconductor or the matrix material may comprise spiro-MeOTAD or consist of spiro-MeOTAD, ie a compound of the formula (III) which is commercially available, for example, from Merck KGaA, Darmstadt, Germany, Taiwan:

O

Alternatively or additionally, other p-ha! Bleitende compounds, in particular low molecular weight and / or oligomeric and / or polymeric p-semiconducting compounds can be used.

According to an alternative embodiment, the low molecular mass organic p-type semiconductor or the matrix material comprises one or more compounds of the abovementioned general formula I, wherein, for example, reference may be made to the subsequently published PCT application with the number PCT / EP2010 / 051826. The p-type semiconductor may contain the at least one compound of the above-mentioned general formula I additionally or alternatively to the above-described spiro compound.

The term "alkyl" or "alkyl group" or "alkyl radical" as used in the context of the present invention is to be understood as meaning generally substituted or unsubstituted C 1 -C 20 -alkyl radicals, preference being given to C 1 -C 10 -alkyl radicals, particularly preferably C 1 -C 8 -alkyl radicals The alkyl radicals may be both unbranched and branched In addition, the alkyl radicals having one or more substituents may be selected from the group consisting of C 1 -C 20 -alkoxy, halogen, preferably -F, and C 6 -C 30 -alkyl radicals. Aryl, which in turn may be substituted or unsubstituted, be substituted. Examples of suitable alkyl groups are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl and also isopropyl, isobutyl, isopentyl, sec-butyl, tert-butyl, neopentyl, 3,3-dimethylbutyl, 2-ethylhexyl and C6- C30-aryl, C1-C20-alkoxy and / or halogen, in particular F, substituted derivatives of said alkyl groups, for example -CF3.

The term "aryl" or "aryl group" or "aryl" as used in the present invention are optionally substituted, C6-C30 aryl radicals are to be understood that of monocyclic, bicyclic, tricyclic and multicyclic aromatic rings Preferably, the aryl moiety contains 5- and / or 6-membered aromatic rings, unless they are monocyclic systems, the term aryl for the second ring also includes the saturated form (perhydroform or the partially unsaturated form (for example, the dihydroform or tetrahydroform), if the respective forms are known and stable. Thus, the term aryl for the purposes of the present invention also includes, for example, bicyclic or tricyclic radicals in which both both and all three radicals are aromatic, as are bicyclic or tricyclic radicals in which only e in ring is aromatic as well as tricyclic radicals wherein two rings are aromatic. Examples of aryl are phenyl, naphthyl, indanyl, 1, 2-dihydronaphthenyl, 1, 4-dihydronaphthenyl, fluorenyl, indenyl, anthracenyl, phenanthrenyl or 1, 2,3,4-tetrahydronaphthyl. Particularly preferred are C6-C10-aryl radicals, for example phenyl or naphthyl, very particularly preferably C6-aryl radicals, for example phenyl. Furthermore, the term aryl also includes ring systems comprising at least two monocyclic, bicyclic or multicyclic aromatic rings linked together via single or double bonds. As an example his biphenyl groups called.

The term "heteroaryl" or "heteroaryl group" or "heteroaryl" as used in the present invention are to be understood as meaning optionally substituted 5- and 6-membered aromatic rings as well as multicyclic rings, for example bicyclic or tricyclic compounds The heteroaryls in the invention preferably contain 5 to 30 ring atoms They may be monocyclic, bicyclic or tricyclic and may be derived in part from the abovementioned aryl in which at least one aryl skeleton is present in the aryl skeleton Preferred heteroatoms are N, O and S. Particularly preferably, the hetaryl radicals have 5 to 13 ring atoms, more preferably the backbone of the heteroaryl radicals is selected from systems such as pyridine and five-membered heteroaromatics such as thiophene, pyrrole, imidazole or Furan.These skeletons can be given lls be fused with one or two six-membered aromatic radicals. Furthermore, the term heteroaryl also includes ring systems comprising at least two monocyclic, bicyclic or multicyclic aromatic rings which are linked together via single or double bonds, wherein at least one ring contains a heteroatom. Unless they are monocyclic systems, in the term heteroaryl for at least one ring, the saturated form (perhydroform) or the partially unsaturated form (for example, the dihydroform or tetrahydroform), if the respective forms are known and stable, is possible , Thus, for the purposes of the present invention, the term heteroaryl also includes, for example, bicyclic or tricyclic radicals in which both both and all three radicals are aromatic, as well as bicyclic or tricyclic radicals in which only one ring is aromatic, and tricyclic radicals in which two Rings are aromatic, wherein at least one of the rings, ie at least one aromatic or a non-aromatic ring having a heteroatom. Suitable fused heteroaromatics are, for example, carbazolyl, benzimidazolyl, benzofuryl, dibenzofuryl or dibenzothiophenyl. The backbone may be substituted at one, several or all substitutable positions, with suitable substituents being those already mentioned under the definition of Ce-cao-aryl. However, the hetaryl radicals are preferably unsubstituted. Suitable hetaryl radicals are, for example, pyridin-2-yl, pyridin-3-yl, pyridin-4-yl, thiophen-2-yl, thiophen-3-yl, pyrro-2-yl, pyrrol-3-yl, furan -2-yl, furan-3-yl and imidazol-2-yl and the corresponding benzanellierten radicals, in particular carbazolyl, benzimidazolyl, benzofuryl, dibenzofuryl or dibenzothiophenyl.

In the context of the invention, the term "optionally substituted" refers to radicals in which at least one hydrogen radical of an alkyl group, aryl group or heteroaryl group has been replaced by a substituent As far as the nature of this substituent is concerned, preference is given to alkyl radicals, such as, for example, methyl, ethyl , Propyl, butyl, pentyl, hexyl, heptyl and octyl and isopropyl, isobutyl, isopentyl, sec-butyl, tert-butyl, neopentyl, 3,3-dimethylbutyl and 2-ethylhexyl, aryl radicals, such as C6-C10- Aryl radicals, in particular phenyl or naphthyl, very particularly preferably C 6 -aryl radicals, for example phenyl, and hetaryl radicals, for example pyridin-2-yl, pyridin-3-yl, pyridin-4-yl, thiophene-2 yl, thiophen-3-yl, pyrrol-2-yl, pyrro-3-yl, furan-2-yl, furan-3-yl and imidazol-2-yl and the corresponding benzanellated radicals, in particular carbazolyl, benzimidazolyl, benzofuryl, Dibenzofuryl or dibenzothiophenyl may also be mentioned by way of example, the following substituents are g alkenyl, alkynyl, halogen, hydroxyl.

The degree of substitution can vary from simple substitution to the maximum number of possible substituents.

Preferred compounds of the formula I to be used according to the invention are characterized in that at least two of the radicals R, R ² and R ^{3 are} para-substituted -OR and / or NR 2 substituents. In this case, it may be at least two residues either only to -OR radicals, only -NR2 radicals or at least one -OR and at least one - act NR2 radical.

Particularly preferred compounds of the formula I to be used according to the invention are characterized in that at least four of the radicals R, R ² and R ^{3 are} para-substituted -OR and / or -NR 2 substituents. In this case, the at least four radicals may be either only -OR radicals, only -NR 2 radicals or a mixture of -OR and -NR 2 radicals. Very particularly preferred compounds of the formula I to be used according to the invention are distinguished by the fact that all radicals R ¹ , R ² and R ^{3 are} para-substituted -OR and / or -NR 2 substituents. These may be either only -OR radicals, only -NR ₂ radicals or a mixture of -OR and -NR ₂ radicals. In all cases, the two Rs in the -NR2 groups may be different from each other, but they are preferably the same.

Preferably, A ¹ , A ² and A ^{3 are} independently selected from the group consisting of

where m is an integer value from 1 to 18,

Alkyl, aryl or heteroaryl, where R ^{4 is} preferably an aryl radical, more preferably a phenyl radical,

R ⁵ , R ⁶ independently of one another are H, alkyl, aryl or heteroaryl, wherein the aromatic and heteroaromatic rings of the structures shown may optionally be further substituted. The degree of substitution of the aromatic and heteroaromatic rings can vary from simple substitution to the maximum number of possible substituents.

Preferred substituents in the case of a further substitution of the aromatic and heteroaromatic rings are the substituents already mentioned above for the one, two or three optionally substituted aromatic or heteroaromatic groups.

Preferably, the aromatic and heteroaromatic rings of the structures shown are not further substituted.

Particularly preferred are A, A ² and A ³ , independently of one another, further

Particularly preferably, the at least one compound of the forms! (I) one of the following structures:

According to an alternative embodiment, the matrix material is ID322, ie

a compound of formula (IV):

The compounds to be used according to the invention can be prepared by customary methods of organic synthesis known to those skilled in the art. References to relevant (patent) references are also found in the Synthesis Examples below.

At least one of the electrodes can be made transparent. Thus, for example, the first electrode may be designed as a working electrode and the second electrode as a counter electrode or vice versa. One or both of these electrodes can be made transparent. In particular, the photovoltaic element may comprise at least one layer structure applied to a substrate, the layer structure comprising the first electrode, the n-semiconductive metal oxide, the dye, the fixed layer. The organic p-type semiconductor may include with the metal oxide and the at least one second electrode in the order named or in reverse order.

In particular, the n-semiconducting metal oxide can be made porous, wherein between the n-semiconductive metal oxide and the first electrode, in particular, at least one buffer layer of a metal oxide can be introduced. This buffer layer can be used, for example, as a dense layer, i. as a non-particulate layer. For example, this buffer layer can be applied by means of a PVD method, for example a vapor deposition method and / or a sputtering method. Alternatively or additionally, other methods can also be used, for example CVD methods and / or spray pyrolysis methods. On the other hand, the n-semi-conducting metal oxide is preferably applied by means of a paste process, for example by printing, spin-coating or knife-coating a paste of an n-semiconductive metal oxide. This paste can then be sintered by at least one temperature treatment step, for example by heating to above 200 ° C, in particular to above 400 ° C, for example 450 ° C. In this sintering, for example, volatile constituents of the paste can be removed, so that preferably only the n-semiconductive metal oxide particles remain. As described above, the dye may be applied to the n-type semiconductive metal oxide in particular. This application is preferably carried out in such a way that the dye completely or partially penetrates an n-semiconducting metal oxide layer, for example a particulate layer, in order to sensitize the particles of the n-semiconductive metal oxide, for example by forming one or more layers of the dye on these particles be, for example, monomolecular layers. Accordingly, the application of the dye may, for example, be effected by means of at least one impregnation process, for example by immersing a sample comprising the n-type semiconducting metal oxide layer in a solution of the dye. Other impregnation methods can also be used.

As a particular advantage of the present invention, the photovoltaic element may in particular comprise at least one Verkapseiung. In contrast to conventional photovoltaic elements in which solid p-type semiconductors are doped with oxygen (for example by storage in air), those in which the silver in oxidized form, for example the at least one silver (l) salt [Ag ⁺ ] _m [ A ^m -] and particularly preferably the silver bis (trifluoromethylsulfonyl) imide, doped p-Halibleiter exist even without such an oxygen atmosphere for a long time. Accordingly, a Verkapseiung can be applied, which shields the photovoltaic element, in particular the electrodes and / or the p-type semiconductor, against an ambient atmosphere. In this way, despite the doping by means of the silver in oxidized form, in particular of the at least one silver (I) salt, [Ag ⁺ ] _m [A ^m ] and particularly preferably the silver bis (trifluoromethylsulfonyi) imide, improved properties of the p-type semiconductor, an exclusion of oxygen, whereby, for example, one or more of the electrodes are protected against negative effects by oxygen and / or other ambient gases. For example, in this way an electrode degradation can be prevented. The encapsulation can comprise, for example, an encapsulation by a solid capsule element, for example a plane or at least one well equipped capsule, which is applied for example to the layer structure that this completely or partially surrounds the layer structure. For example, an edge of the encapsulation may completely or partially enclose the layer structure and may be connected to the substrate, for example, by a bond and / or another connection, preferably a material connection. Alternatively or additionally, the encapsulation may also comprise one or more layers of a material which prevents the penetration of harmful environmental influences, for example moisture and / or oxygen. For example, organic and / or inorganic coatings can be applied to the layer structure. A shield from the ambient atmosphere can generally be understood to mean a slowing down of the penetration of gases and / or moisture from the ambient atmosphere into the layer structure. The slowing down can, for example, take place in such a way that concentration differences within and outside the encapsulation are only compensated within several hours, preferably several days, in particular even several weeks, months up to years.

The dye-sensitized solar cell may further comprise, in particular, at least one passivation material between the n-semiconductive metal oxide and the p-type semiconductor. In particular, this passivation material may be configured to at least partially prevent electron transfer between the n-type semiconducting metal oxide and the p-type semiconductor. The passivation material may in particular be selected from: Α! 2θ3ΐ a silane, in particular CH3SiCl3; an organometallic complex, in particular an Al ³⁺ complex, a 4-tert-butylpyridine; Hexadecylmalonic.

As stated above, in a further aspect of the present invention, a method for producing a solid organic p-type semiconductor for use in an organic device is proposed. This organic component may in particular be a photovoltaic element, for example a photovoltaic element in one or more of the embodiments described above, in particular a dye-sensitized line. However, other embodiments of the organic component are also possible in principle, including the intended use in organic light-emitting diodes, organic transistors, as well as other types of photovoltaic elements, for example organic solar cells. In the proposed method, at least one p-type organic matrix material, for example a matrix material of the type described above, and at least silver in oxidized form, preferably at least one silver (i) salt of the formula [Ag ⁺ ] _m [A ^m " As described above, a p-type organic matrix material is understood to mean an organic material which can preferably be applied from the solution and which is capable of positive charges These positive charges may already be present in the matrix material and may only be increased by the p-doping or may be generated by the p-doping by means of the silver in oxidized form, in particular the matrix material may be stable and reversibly oxidizable and be set up to positive charges ("holes") to other molecules, for example wise adjacent molecules of the same kind to pass. In general, it is noted that the effect of the silver salt is based only on observed effects of an increase in p-conductivity. Accordingly, for example, a carrier density and / or a mobility of positive charges in the p-type semiconductor can be increased by adding the silver in oxidized form. The invention is not limited to the p-doping in a microscopic manner.

The at least one organic matrix material and the silver in oxidized form, in particular the at least one silver (I) salt of the formula [Ag ⁺ ] _m [A ^m as p-dopant, are preferably applied together from at least one liquid phase to the at least one carrier element , as described above. In this case, a carrier element can be understood to be a pure substrate, for example a glass and / or plastic and / or laminate substrate. Alternatively or additionally, however, the carrier element may also comprise further elements, for example one or more electrodes and / or one or more layers, which may already be applied to the substrate. By way of example, the application of the p-type semiconductor from the liquid phase can take place to an already partially or completely finished layer structure, wherein, for example, one or more layers can already be applied to a substrate, whereupon at least one layer of the p-type semiconductor is applied. Thus, for example, on a substrate already described above with respect to the photovoltaic element, the at least one first electrode, the at least one n-type semiconducting metal oxide and preferably the dye applied before applied from the at least one liquid phase of the p-type semiconductor becomes.

The application of a liquid phase may generally include, for example, a wet-chemical processing, for example spin-coating, knife coating, pouring, printing or similar wet-chemical processes or combinations of named and / or other procedures. For example, printing processes such as inkjet printing, screen printing, offset printing or the like can be used. After application from the liquid phase, in particular drying of the p-type semiconductor can take place, for example in order to remove volatile constituents such as solvent of the liquid phase. This drying can be carried out, for example, under the influence of temperature, for example at temperatures of 30 ° C to 150 ° C. However, other embodiments are possible in principle.

In particular, as described above, the matrix material may comprise at least one low molecular weight organic p-type semiconductor, for example as matrix material. In particular, one or more of the organic p-type semiconductors described above may be used. In particular, the low molecular weight organic p-type semiconductor may comprise at least one triphenylamine. The low molecular weight organic p-type semiconductor may in particular comprise at least one spiro compound, for example one or more of the spiro compounds described above.

In addition to the at least one matrix material and the silver in oxidized form, in particular the silver (I) salt of the formula [Ag ⁺ ] _m [A ^m -], the liquid phase may furthermore comprise one or more additional components which have different uses can have. Thus, it is known, for example, for stabilization purposes and / or for improving the electrical properties, to use spiro compounds, for example spiro-MeOTAD, in solution with at least one lithium salt. In general, the liquid phase may accordingly further comprise, for example, at least one metal salt. In particular, this may be a metailorganisches salt. Also a combination of different salts is possible. In particular, lithium salts can be used, for example organometallic lithium salts, preferably LiN (SO 2 CF 3) 2.

The at least one liquid phase may, as described above, in particular comprise at least one solvent. The term solvent is used in the context of the present invention regardless of whether all, several or individual of the components contained in the liquid phase are actually present in dissolved form or if they are present in another form, for example as a suspension, dispersion, emulsion or in others Shape. In particular, the silver in oxidized form, for example the at least one silver (I) salt and particularly preferably the silver bis (trifluoromethylsulfony!) imide, in dissolved form. For example, the at least one matrix material may be dissolved or dispersed. The silver in oxidized form, for example the at least one silver (I) salt [Ag ⁺ ] _m [A ^m ] and particularly preferably the Si! Ber-bis (trifluoromethylsulfonyl) imide, can be present in particular dissolved, but can also be present basically in a different form, for example, dispersed and / or suspended. Particularly preferred is the use of at least one organic solvent. In particular, one or more of the following solvents may be used: cyclohexanone; Chiorobenzol; benzofuran; Cyclopentanone.

The proposed method for producing a solid organic p-type semiconductor may be used in particular for producing the above-described photovoltaic element in one or more of the described embodiments. However, other organic components can be produced by means of the method. A combination with other known methods is also conceivable, so that, for example, if several organic p-type semiconductors are provided, one or more of these p-type semiconductors can be produced by means of the proposed method according to the invention, and one or more of the conventional p-type semiconductors other procedures.

A particular advantage of the proposed method for producing the solid organic p-type semiconductor is that, in contrast to many methods known from the prior art, storage in air is not necessarily required. Thus, the process can be carried out in particular at least partially in an oxygen-poor atmosphere. In the context of the present invention, an organic component is generally understood to mean a component which has one or more organic elements, for example one or more organic layers. In this case, it is possible to use completely organic components, for example components in which the layer structure-if appropriate with the exception of the electrodes-comprises only organic layers. However, it is also possible to produce hybrid components, for example components which comprise one or more inorganic layers in addition to one or more organic layers. When the proposed method for producing the solid organic p-type semiconductor is used in a multi-step manufacturing process, one, several or all of the process steps for producing the organic device may be performed in an oxygen-poor atmosphere. In particular, the process step of producing the solid organic p-type semiconductor may be carried out in the low-oxygen atmosphere, in contrast to the known processes described above. In particular, the application of the liquid phase to the carrier element in the low-oxygen atmosphere can thus be carried out. Under an oxygen-poor atmosphere is generally an atmosphere to understand, which has a reduced Sauerstoffanteii compared to the ambient air. For example, the low-oxygen atmosphere may have an oxygen content of less than 1000 ppm, preferably less than 500 ppm, and more preferably less than 100 ppm, for example 50 ppm or less. Also, a further processing of the organic component, for example, the Dye solar cell, be carried out under such an oxygen-poor atmosphere. Thus, for example, at least after the application of the solid p-type semiconductor by means of the proposed method, the oxygen-poor atmosphere can not be interrupted until after the encapsulation. Complete processing of the entire component in the low-oxygen atmosphere is also possible without adversely affecting the electrical properties of the component. Particularly preferred is an oxygen-poor atmosphere in the form of an inert gas, for example a nitrogen atmosphere and / or an argon atmosphere. Mixed gases can also be used.

As stated above, in a third aspect of the present invention, a method of manufacturing a photovoltaic element is proposed. This may in particular be a photovoltaic element according to one or more of the embodiments described above, for example a Farbstoffsoiarzelle. The proposed method for producing the photovoltaic element can be carried out in particular using the method described above for producing a solid organic p-type semiconductor, wherein the method for producing the solid organic p-type semiconductor is one or more times in the proposed method for producing the photovoltaic Elements can be used. However, a use of other methods is possible in principle.

The proposed method preferably has the procedural steps described below, which can preferably, but not necessarily, be carried out in the order shown. Individual or several method steps are also overlapping in time and / or parallel feasible. Furthermore, the implementation of additional, not described process steps is possible. The proposed method provides at least one first electrode, at least one n-semiconducting etalloxide, at least one dye which absorbs electromagnetic radiation, at least one solid organic p-type semiconductor and at least one second electrode. This provision can be made, for example, in the order mentioned. In particular, the provision can be effected by producing a layer structure, for example as described above. This layer structure can be constructed, for example, successively on one or more substrates. In this case, one or more of the mentioned elements can also be combined to form a common layer, for example the n-semiconductive metal oxide and the dye.

In the proposed method, the p-type semiconductor is designed such that this silver in oxidized form, for example the at least one silver (I) salt [Ag ⁺ ] _m [A ^m -] and particularly preferably the silver bis ( trifluoromethylsulfonyl) imide. In particular, the p-type semiconductor may comprise at least one organic matrix material which is oxidized by the silver, for example the at least one silver (I) salt [Ag ⁺ ] _m [A ^m -] and more preferably the silver bis (trifluoromethylsulfonyl ) imid doped. For possible embodiments of the organic matrix material and / or the silver in oxidized form, for example of the at least one silver (I) salt [Ag ⁺ ] _m [A ^m -] and particularly preferably the silver bis (trifluoromethylsulfonyl) imide, can the above and below description are referenced. In particular, the p-type semi-conductor can be produced by a method in which wet-chemical processing is used, for example, according to the above description of the method for producing the solid organic p-type semiconductor. In this wet-chemical processing, at least one p-type organic matrix material and the silver in oxidized form, for example the at least one silver (l) salt [Ag ⁺ ] _m [A ^m -] and particularly preferably the silver bis (trifluoromethylsulfonyl) imid, applied as p-type dopant from at least one liquid phase together on at least one carrier element.

In the following, further optionally realizable embodiments of the photovoltaic element as well as of the methods which are particularly preferred within the scope of the invention are described. However, other embodiments are possible in principle.

The photovoltaic element may in particular comprise a layer structure, which may be applied, for example, to a substrate. In this case, for example, the first electrode or the second electrode can be assigned to the substrate. At least one of the electrodes should be made transparent. In this context, a "transparent" electrode is to be understood in particular as meaning that within the visible spectral range and / or in the region of the solar spectrum (about 300 nm to 2000 nm) there is a transmission of at least 50%, preferably of at least 80%. If the substrate is designed as a transparent substrate, in particular the electrode assigning the substrate should be made transparent.

The substrate may be or include, for example, a glass substrate and / or a plastic substrate. However, other materials, including a combination of different materials, are in principle applicable, for example laminates. The constituents of the photovoltaic element can be applied as layers directly or indirectly to the substrate. In the context of the present invention, the terms of a carrier element, a carrier and a substrate are used at least largely synonymously. If a carrier element is mentioned, this rather emphasizes the possibility that a layer is applied indirectly to the substrate, so that there is a difference between the layer to be applied and the actual substrate at least one further element, in particular at least one further layer can be located. However, a direct application is possible.

The photovoltaic element can in particular be designed as a dye solar cell. Accordingly, in the following, the photovoltaic element is also generally referred to as a "cell", without being restricted to a specific layer structure A cell may in particular comprise the at least one first electrode, the n-type metal oxide, the dye, the p-type semiconductor and The n-type metal oxide, the dye, and the p-type semiconductor may also be referred to as functional layers which may be embedded between the electrodes In addition, the cell may comprise one or more further layers, for example also attributable to the functional layers One or more cells may be directly or indirectly applied to a substrate The photovoltaic element may in particular comprise one or more cells, in particular a single-celled structure or else a multicellular structure, for example a tandem-cell structure with several parallel ones and/ or one above the other on the substrate arranged cells.

In particular, the photovoltaic element according to the present invention may be configured in one or more of the following ways. The embodiments of the elements of the photovoltaic element can also be combined in virtually any desired manner.

First electrode and n-type semiconducting metal oxide

As the n-type semiconductor of the dye solar cell, a single metal oxide or a mixture of various oxides may be used. It is also possible to use mixed oxides. In particular, the n-semiconducting metal oxide may be porous and / or be used as a nanoparticulate oxide, nanoparticles in this context meaning particles having an average particle size of less than 0.1 micrometers. A nanoparticulate oxide is usually applied to a conductive substrate (i.e., a substrate having a conductive layer as a first electrode) by a sintering process as a high surface area, thin porous film.

The substrate may be rigid or flexible. In addition to metal foils, plastic substrates or foils and, in particular, glass plates or glass foils are suitable as substrate (hereinafter also referred to as carrier). Suitable electrode materials, in particular for the first electrode according to the preferred structure described above, are in particular conductive materials such as transparent conductive oxides (TCOs), for example doped with fluorine and / or indium. Tin oxide (FTO or (TO) and / or aluminum-doped zinc oxide (AZO), carbon nanotubes or metal films) Alternatively, or in addition, thin metal films that still have sufficient transparency could be used Since the structure proposed usually requires only a single substrate, it is also possible to construct flexible cells, which makes it possible to use a large number of applications which would not be feasible or would be difficult to achieve with rigid substrates, such as For example, the use in bank cards, garments, etc. The first electrode, in particular the TCO layer may additionally be coated or coated with a (for example 10 to 200 nm thick) solid metal oxide buffer layer to direct contact of the p-type semiconductor with the TCO layer (see Peng et al., Coord. Chem. Rev. 248, 1479 (2004)) However, the use of solid p-type semiconducting electrolytes, in which contact of the electrolyte with the first electrode is greatly reduced compared to liquid or egg-shaped electrolytes, renders this buffer layer unnecessary in many cases, so that this layer also has a current-limiting effect and also deteriorate the contact of the n- semi! eitenden metal oxide with the first electrode, can be dispensed with in many cases. This increases the efficiency of the components. On the other hand, such a buffer layer can in turn be used selectively to adapt the substream of the dye-sensitized solar cell to the substream of the organic solar cell. Furthermore, in rows in which the buffer layer has been dispensed with, in particular in solid cells, problems with undesired recombinations of charge carriers frequently occur. In this respect, buffer layers, especially in solid cells, are advantageous in many cases.

As is generally known, thin layers or films of metal oxides are generally inexpensive solid semiconductor materials (n-type semiconductors), but their absorption due to large band gaps is usually not in the visible range of the electromagnetic spectrum but mostly in the ultraviolet spectral range. For use in solar cells, the metal oxides therefore generally have to be combined with a dye as photosensitizer, as is the case with the dye-cell solar cells, which absorbs in the wavelength range of sunlight, ie at from 300 to 2000 nm, and in the electronically excited state electrons injected into the conduction band of the semiconductor. By means of a solid p-type semiconductor additionally used in the cell as the electrolyte, which in turn is reduced at the counterelectrode (or at a tandem solar cell at the transition to the second subcell), electrons can be returned to the sensitizer so that it is regenerated.

Of particular interest for use in solar cells are the semiconductors zinc oxide, tin dioxide, titanium dioxide or mixtures of these metal oxides. The metal oxides can be used in the form of nanocrystalline porous layers. These layers have a large surface, which is coated with the dye as a sensitizer, so that a high absorption of sunlight is achieved. Structured metal oxide layers, such as nanorods, offer advantages such as higher electron mobilities or improved pore filling by the dye.

The metal oxide semiconductors can be used alone or in the form of mixtures. It is also possible to coat a metal oxide with one or more other metal oxides. Furthermore, the metal oxides may also be used as a coating on another semiconductor, e.g. GaP, ZnP or ZnS, be applied.

Particularly preferred semiconductors are zinc oxide and titanium dioxide in the anatase modification, which is preferably used in nanocrystalline form.

In addition, the sensitizers can advantageously be combined with all n-type semiconductors commonly used in these solar cells. Preferred examples are metal oxides used in the ceramic, such as titanium dioxide, zinc oxide, tin (IV) oxide, tungsten (VI) oxide, tantalum (V) oxide, niobium (V) oxide, cesium oxide, strontium titanate, zinc stannate, complex oxides of perovskite Type, eg Barium titanate, and called binary and ternary iron oxides, which may also be present in nanocrystalline or amorphous form.

Due to the strong absorption exhibited by conventional organic dyes as well as phthalocyanines and porphyrins, even thin layers or films of the n-type semiconducting metal oxide are sufficient to take up the required amount of dye. Thin metal oxide films in turn have the advantage that the probability of undesired recombination processes decreases and that the internal resistance of the dye subcell is reduced. For the n-half! Eitende metal oxide layer thicknesses of 100 nm can be used to 20 microns preferably, more preferably in the range between 500 nm to about 3 micrometers. dye

The terms of the dye, the sensitizer dye and the sensitizer are used synonymously in the context of the present invention, as is customary in DSCs, without being limited to possible embodiments. Numerous dyes that can be used in the context of the present invention are known from the prior art, so that for possible material examples, reference may also be made to the above description of the prior art for dye-sensitized solar cells. All listed and claimed dyes may in principle also be present as pigments. Color-sensitized solar cells based on titanium dioxide as capping material are described, for example, in US Pat. Nos. 4,927,721, Nature 353, pp. 737-740 (1991) and US Pat. No. 5,350,644 and Natura 395, p. 583- 585 (1998) and EP-A-1 176 646. The words used in these documents In principle, written dyes can also be used advantageously in the context of the present invention. These dye-sensitized solar cells preferably contain monomolecular films of transition metal complexes, in particular ruthenium complexes which are bonded to the titanium dioxide layer via acid groups, as sensitizers.

Sensitizers, not least for cost reasons, have repeatedly been proposed as metail-free organic dyes, which are likewise also usable in the context of the present invention. High efficiencies of over 4%, especially in solid dye-dye solar cells, can be achieved, for example, with indoline dyes (see, for example, Schmidt-Mende et al., Adv. Mater., 2005, 17, 813). US Pat. No. 6,359,211 also describes the use, within the scope of the present invention, of cyanine, oxazine, thiazine and acridine dyes which have carboxyl groups bonded via an alkylene radical for attachment to the titanium dioxide semiconductor. Organic dyes have now reached efficiencies of nearly 12.1% in liquid cells (see, e.g., Wang et al., ACS., Nano 2010). Also, pyridinium-containing dyes have been reported, can be used in the present invention, and show promising efficiencies. Particularly preferred sensitizing dyes in the proposed dye solar cell are the perylene derivatives, terrylene derivatives and quatterylene derivatives described in DE 10 2005 053 995 A1 or WO 2007/054470 A1. The use of these dyes leads to photovoltaic elements with high efficiencies and high stabilities.

The rylenes show strong absorption in the wavelength range of the sunlight and can, depending on the length of the conjugated system, a range of about 400 nm (perylene derivatives I from DE 10 2005 053 995 A1) up to about 900 nm (quaterrylene derivatives I from DE 10 2005 053 995 A1). Depending on their composition, terrylene-based rylene derivatives I absorb in a solid state adsorbed to titanium dioxide in a range from about 400 to 800 nm. In order to maximize the utilization of the irradiated sunlight from the visible to the near-infrared range, it is advantageous to use mixtures of various types Rylene derivatives I use. Occasionally, it may also be advisable to use different Rylenhomologe.

The rylene derivatives I can easily and permanently be fixed on the n-type semiconducting metal oxide film. Binding takes place via the anhydride function (x1) or the carboxyl groups -COOH or -COO- formed in situ or via the acid groups A contained in the imide or condensate residues ((x2) or (x3)) In DE 10 2005 053 995 A1 described Rylenderivate I are well suited for use in dye-sensitized solar cells in the context of the present invention.

It is particularly preferred if the dyes have an anchor group at one end of the molecule which ensures their fixation on the n-semiarite film. At the other end of the molecule, the dyes preferably contain electron donors Y, which facilitate regeneration of the dye after electron donation to the n-type semiconductor and also prevent recombination with electrons already released to the semiconductor.

For further details on the possible selection of a suitable dye, reference may again be made, for example, to DE 10 2005 053 995 A1. Ruthenium complexes, porphyrins, other organic sensitizers and preferably rylenes can be used in particular for the tandem cells described here.

The fixation of the dyes on or in the n-semiconducting Metalloxidfiimen can be done in a simple manner. For example, the n-type semiconductive metal oxide films in freshly sintered (still hot) condition for a sufficient period of time (e.g., about 0.5 to 24 hours) may be contacted with a solution or suspension of the dye in a suitable organic solvent. This can be done, for example, by immersing the metal oxide-coated substrate in the solution of the dye.

If combinations of different dyes are used, they can be applied, for example, one after the other from one or more solutions or suspensions containing one or more of the dyes. Also possible is the use of two dyes separated by a layer of e.g. CuSCN are (see, for example, Tennakone, K.J., Phys. Chem B. 2003, 107, 13758). The most appropriate method can be determined comparatively easily in individual cases.

When selecting the dye and the size of the oxide particles of the n-semiconducting metal oxide, the solar cell should be designed so that as much light as possible is absorbed. The oxide layers should be structured so that the solid p-type semiconductor can fill the pores well. Thus, smaller particles have larger surfaces and are therefore able to adsorb a larger amount of dyes. On the other hand, larger particles generally have larger pores that allow better penetration through the p-type conductor.

As described above, the proposed concept involves the use of one or more solid p-type semiconductors. In order to prevent a recombination of the electrons in the n-semiconducting metal oxide with the solid p-conductor, it is possible to distinguish between the n- semiconducting metal oxide and the p-type semiconductor at least one passivating layer are used, which has a passivation material. This layer should be as thin as possible and, if possible, should only cover the hitherto uncovered areas of the n-semiconducting metal oxide. The passivation material may also be applied to the metal oxide in time before the dye. As passivation materials, in particular one or more of the following substances are preferred: Al ₂ O ₃ ; Silanes, such as CH ₃ SiCl ₃ ; Al ³⁺ ; 4-tert-butylpyridine (TBP); MgO; GBA (4-guanidino-butyric acid) and similar derivatives; alkyl acids; Hexadecylmalonic acid (HDMA). p-type semiconductor

As described above, one or more solid organic p-type semiconductors are used in the context of the photovoltaic element proposed here - in isolation or else in combination with one or more further p-type semiconductors of organic or inorganic type. The pseudofiber comprises at least one solid organic p-type semiconductor as described above, at least silver in oxidized form. In the context of the present invention, a p-type semiconductor is generally understood to mean a materal valley, in particular an organic material which is capable of conducting holes. In particular, it may be an organic material having an extended ττ electron system which can be stably oxidized at least once, for example, forming a so-called radical cation. By way of example, the p-type semiconductor may comprise at least one organic matrix material which has the properties mentioned. In particular, the p-type semiconductor may be p-doped by the silver (1). This means that an already existing p-semieitende property of the p-type semiconductor or of the matrix material is reinforced by the doping with silver (l) or even created. In particular, the doping can increase a charge carrier density, in particular a hole density. Alternatively or additionally, a mobility of the charge carriers, in particular of the holes, can be influenced by the doping, in particular increased.

In particular, the doped p-type semiconductor as described above can be prepared or prepared by applying at least one p-type organic material and silver in oxidized form to at least one support element, wherein the silver in oxidized form is preferably in the form of at least one silver (l ) Salt [Ag ⁺ ] m [A ^m ] is applied to at least one support element, wherein A ^m - is the anion of an organic or inorganic acid, and m is an integer in the range of 1 to 3, preferably wherein m is 1 is.

As far as the integer m is concerned, m is preferably 1 or 2, more preferably 1. Accordingly, a salt of the formula Ag ⁺ A- is used to prepare the p-type semiconductor. As far as A ^m - is concerned, it is preferably an anion of an organic or inorganic acid. According to a preferred embodiment, A ^m - is an anion of an organic acid, wherein the organic acid preferably contains at least one fluoro group or cyano group, (-CN) particularly preferably at least one fluoro group. [A ^m -] is preferably the anion of an organic carboxylic acid, sulfonic acid, phosphonic acid or sulfonic acidimide, preferably containing at least one fluoro group or cyano group.

Preferably, the present invention relates to a photovoltaic element as described above, wherein [A ^m -] has a structure of the formula (II),

O

R ^a -SX

Wherein R ^{a is} a fluoro group -F or a substituted by at least one fluoro group or a cyano group, alkyl radical, cycloalkyl radical, aryl radical or heteroaryl radical, and wherein X is -O or N ^~ -R ^b j _s t, and wherein R ^b comprises a fluoro group -F or a cyano group, and wherein R ^b further comprises a group of the formula -S (0) 2-.

The term cycloalkyl radical or cycloalkyl group as used in the present invention refers to cyclic, optionally substituted, alkyl groups, preferably 5 or 6-membered rings or multicyclic rings, more preferably having 5 to 20 carbon atoms.

Rest R ^a :

According to a preferred embodiment of the invention, R ^{a is} -F or a, at least one fluoro group or a cyano group, preferably at least one fluoro group, substituted alkyl radical, most preferably one with at least one fluoro group or a cyano group, preferably a fluoro group, substituted methyl group , Ethyl group or propyl group. In addition to the fluorine group or the cyano group, the alkyl radical may contain at least one further substituent. R ^a preferably contains at least 3 fluorine substituents or a cyano group, preferably at least 3 fluorine substituents. R ^a is especially selected from the group consisting of -F, -CF 3, -CF 2 -CF 3 and -CH 2 -CN, more preferably selected from the group consisting of -F, -CF 3 and -CF 2 -CF 3.

Accordingly, the present invention also relates to a photovoltaic element as described above, wherein [A ^m -] has a structure selected from the following formulas,

O O 0

FSX F3C-SX F ₃ CF ₂ CSX

 Ö O 0

and wherein X is -O- or-N -R ^b. Most preferably, R ^a is -CF ₃ . Rest R ^b :

As described above, R ^{b is} a group comprising a fluoro group -F or a cyano group, wherein R ^b further comprises a group of the formula -S (0) 2-. Preferably, R ^b comprises at least one alkyl, cycloalkyl, aryl or heteroaryl radical, wherein the alkyl, cycloalkyl, aryl or heteroaryl radical is in each case substituted by at least one fluoro group -F or one cyano group, preferably by at least one fluoro group and where R ^b further comprises a group of the formula -S (0) 2-.

Preferably, R ^{b has} a structure of the following formula:

O

 - S-R

 I i

O wherein R ^{bb is} -F or a, with at least one fluorine group or a cyano group, preferably at least one fluoro group, substituted alkyl group, more preferably a substituted with at least one fluorine group methyl group, ethyl group or propyl group. In addition to the fluoro group and / or cyano group, the alkyl radical may contain at least one further substituent. Preferably, R ^b contains at least 3 fluoro substituents.

R ^bb is in particular selected from the group consisting of -F, -CF ₃ , -CF ₂ -CF ₃ and -S (O) 2-CH ₂ -CN, in particular selected from the group consisting of -F, -CF ₃ and -CF 2 - CF3. Accordingly, the present invention also relates to a photovoltaic element as described above, wherein X is - N ^" - R ^b , and wherein R ^{b is} selected from the group consisting of -S (0) 2-F, -S (0) ₂ -CF ₃ , -S (O) ₂ -CF ₂ -CF ₃ and -S (O) 2-CH ₂ -CN, especially selected from the group consisting of -S (O) 2-F, -S (0 ) ₂ -CF 3, and -S (O) ₂ -CF ₂ -CF ₃ .

[A ^m -] therefore very particularly preferably has one of the following structures:

O O O O

I I I I I I O O

R ^a -SN ^" -SF R ^a -SN -S-CF ₃ R ^a -SN ^" -S-CF ₂ CF ₃

 I I I I I I I I I

O O O O O

wherein R ^{a is} in particular selected from the group consisting of -F, -CF 3 and - CF 2 -CF 3. That XN ^~ -R ^b and R b are preferably in the case of the structure

O

 - S-R

 I i

O, R ^a and R ^{bb are the} same; [A ^m ] is therefore particularly preferably a symmetrical sulfonylic acid imide. Accordingly, in a preferred embodiment, [A ^m -] is selected from bis (trifluoromethylsulfonyl) imide (TFSI), bis (trifluoroethylsulfonyl) imide, and bis (fluorosulfonyl) imide.

According to an alternative embodiment, the present invention relates to a photovoltaic element as described above, wherein [A ^m ] is a trifluoroacetate group. In a further preferred embodiment, [A ™ -] is the anion of an inorganic acid. In this case, [A ^m -] is preferably -NO 3 - (nitrate). Accordingly, the present invention also relates to a photovoltaic element which, as described above, preparable or prepared by introducing, in particular mixing and / or dissolving, at least one silver (l) salt [Ag ⁺ ] _m [A ^m ] in at least one organic matrix material (128), where [A ^m -] is a -NO 3 "group and where m = 1.

Accordingly, the present invention also relates to a photovoltaic element as described above, wherein [A ^m -] selected from the group consisting of bis (trifluoromethylsulfonyl) imide (TFSI ^" ), bis (trifluoroethylsulfony!) Imide, bis (fluorosulfonyl) imide, trifluoromethylsulfonate where [A ^m ] is bis (trifluoromethylsulfonyl) imide (TFSI-). Solid p-type semiconductors doped with at least silver in oxidized form, for example the at least one silver (I) salt [Ag ⁺ ] _m [A ^m ] and particularly preferably the silver bis (trifluoromethylsulfonyl) imide, may be present in the photovoltaic compounds according to the invention Elements are also used without a large increase in cell resistance, especially when the dyes absorb strongly and therefore require only thin n- Ha! Bleiterschichten. In particular, the p-type semiconductor should essentially have a closed, dense layer, so that undesired recombination reactions resulting from contact between the n-semiconducting metal oxide (in particular in nanoporous form) with the second electrode and / or further elements of the photovoltaic element could be reduced.

The silver in oxidized form, for example, the at least one silver (I) salt [Ag ⁺ ] _m [A ^m ] and particularly preferably the silver bis (trifluoromethylsulfonyl) imide, in particular together with the matrix material from the liquid phase Carrier element are applied. For example, the silver in oxidized form, for example the at least one silver (I) salt [Ag ⁺ ] _m [A ^m ] and particularly preferably the silver bis (trifluoromethylsulfonyl) imide, can be processed as a solution, dispersion or suspension Combination with a p-semiconducting matrix material. Optionally, this at least one liquid phase (wherein several liquid phases can also be provided) may be added to at least one organic salt, for example for stabilization purposes and / or for improving the electrical properties.

An important factor which influences the selection of the p-type semiconductor is the hole mobility, since this determines the hole diffusion length (see Kumara, G., Langmuir, 2002, 18, 10493-10495). A comparison of charge carrier mobilities in various spiro compounds can be found, for example, in T. Saragi, Adv. Funct. Mater. 2006, 16, 966-974.

For the purposes of the present invention, preference is given to using organic (ie low molecular weight, oligomeric or polymeric semiconductors or mixtures of such semiconductors) semiconductors. Particularly preferred are p-type semiconductors which can be processed from a liquid phase. Examples here are p-type semiconductors based on polymers such as polythiophene and polyarylamines, or of amorphous, reversibly oxidizable, nonpolymeric organic compounds, such as the spirobifluorenes mentioned at the beginning (cf., for example, US 2006/0049397 and the spiro compounds disclosed herein as p-type semiconductors, which can also be used in the context of the present invention). Preferably, low molecular weight organic semiconductors are used. The solid p-type semiconductors can be used in doped form with silver in oxidized form, for example the at least one silver (I) salt [Ag ⁺ ] _m [A ^m -] and particularly preferably the silver bis-itrifluoromethylsulfonyimide, as dopant , Furthermore, reference may also be made to the comments on the p-type semiconducting materials and dopants from the description of the prior art. For the other possible elements and the possible structure of the dye solar cell can be made to a large extent to the above description.

Second electrode

The second electrode may be a bottom electrode to be assigned to the substrate or else a top electrode pointing away from the substrate. Metal electrodes which can comprise one or more metals in pure form or as a mixture / alloy, in particular aluminum or silver, can be used in particular as the second electrode. Also, the use of inorganic / organic mixing electrodes or multi-layer electrodes is possible, such as the use of LiF / Al electrodes.

Furthermore, it is also possible to use electrode concepts in which the quantum efficiency of the components is increased by forcing the photons through corresponding reflections to pass through the absorbing layers at least twice. Such layer structures are also referred to as "concentrators" and are likewise described, for example, in WO 02/101838 (in particular pages 23-24).

Brief description of the figures

Further details and features of the invention will become apparent from the following description of preferred embodiments in conjunction with the subclaims. In this case, the respective features can be implemented on their own or in combination with one another. The invention is not limited to the exemplary embodiments. The embodiments are shown schematically in the figures. The same reference numerals in the individual figures designate the same or functionally identical or with respect to their functions corresponding elements.

In detail show:

Figure 1 shows a schematic layer structure of an organic photovoltaic element according to the invention in a sectional view in side view;

FIG. 2 shows a schematic arrangement of the energy levels in the layer construction according to FIG. 1; Figure 3 Current-voltage characteristic of a comparative sample without silver in oxidized form, measured 2 days after production;

Figure 4 current-voltage characteristics with Ag-TFSI doping.

embodiments

FIG. 1 shows a highly schematic sectional illustration of a photovoltaic element 110 which, in this exemplary embodiment, is shown in FIG. is formed as dye solar cell 112. The photovoltaic element 1 10 according to the schematic layer structure in Figure 1 can be configured according to the invention. Also, the comparative sample according to the prior art can in principle correspond to the structure shown in Figure 1 and differ from it, for example, only with respect to the solid organic p-type semiconductor. It should be noted, however, that the present invention can also be used in the context of other layer structures and / or in the context of other structures.

The photovoltaic element 110 includes a substrate 14, for example a glass substrate. Other substrates can also be used, as described above. Applied to this substrate 14 is a first electrode 16, which is also referred to as a working electrode and which, as described above, is preferably designed to be transparent. On this first electrode 16, in turn, a blocking layer 118 of an optional metal oxide is applied, which is preferably non-porous and / or non-particulate. On its turn, an n-type semiconducting metal oxide 120 is applied, which is sensitized with a dye 122.

The substrate 1 4 and the layers 1 16 to 120 applied thereon form a carrier element 124 for at least one layer of a solid organic p-type semiconductor 126 applied thereon, which in turn in particular oxidizes at least one p-type semiconducting organic matrix material 128 and at least one silver Form 130, for example, the at least one silver (l) salt [Ag ⁺ ] _m [A ^m ] and particularly preferably the silver bis (trifluoromethylsulfony [) imide, may include. On this p-type semiconductor 126, a second electrode 132 is applied, which is also referred to as the counter electrode. The layers shown in FIG. 1 together form a layer structure 134, which is shielded from an ambient atmosphere by an encapsulation 136, for example in order to completely or partially protect the layer structure 134 from oxygen and / or moisture. One or both of the electrodes 116, 132 may, as indicated in FIG. 1 on the basis of the first electrode 116, be led out of the encapsulation 136 in order to be able to provide one or more contacting surfaces outside the encapsulation 136. In FIG. 2, a highly detailed energy level diagram of the photovoltaic element 110, for example according to FIG. 1, is shown by way of example. Shown are the Fermi levels 138 of the first electrode 116 and the second electrode 132 and the HOMOs (Highest Occupied Molecular Orbital) 140 and the LUMOs (Lowest Unoccupied Molecular Orbital) of the layers 118/120, respectively (which may comprise the same material, for example T1O2) of the dye (exemplified with a HOMO level of 5.7 eV) and the p-type semiconductor 126 (also referred to as HTL, Hole Transport Layer, hole conductor). As materials for the first electrode 1 16 and the second electrode 132 are exemplified FTO (fluorine-doped tin oxide) and silver.

In addition, the photovoltaic elements may optionally comprise further elements. By means of photovoltaic elements 1 10 with or without encapsulation 136, the embodiments described below were realized, by means of which the effect of the present invention and in particular the p-doping of the p-type semiconductor 126 can be occupied by silver in oxidized form 130.

Vergieichsprobe

As a comparative sample of a photovoltaic element, a dye-solid solar cell with solid p-type semiconductor was prepared without doping by silver in oxidized form, as it is known in principle from the prior art. The base material and the substrate used were fluorodoped tin oxide (FTO) coated first 25 mm x 25 mm x 3 mm (Hartford Glass) glass plates coated first with glass cleaner (RBS 35), deionized water and acetone Treated for 5 min in an ultrasonic bath, then boiled for 10 min in iso-propanol and dried in nitrogen Ström.

To prepare an optional solid TiO 2 buffer layer, a spray pyrolysis method was used. Then, as the n-type semiconducting metal oxide, a TiO 2 paste (Dyesol) containing TiO 2 particles having a diameter of 25 nm in a terpineol / ethyl cellulose dispersion was spin-coated at 4500 rpm with a spin coater and at 90 ° C. for 30 minutes dried. After heating at 450 ° C. for 45 minutes and a sintering step at 450 ° C. for 30 minutes, the TiO 2 layer thickness was approximately 1.8 μm.

After removal from the oven, the sample was cooled to 80 ° C and 12 h in a 5 mM solution of an additive ID662 (obtainable, for example, according to Example H) and then for 1 h in a 0.5 mM solution of a dye in dichloromethane dipped. In this case, the dye 1D504 (obtainable, for example, according to Example G) was used as the dye. After removal from the solution, the sample was then rinsed with the same solvent and dried in a stream of nitrogen. The samples thus produced were then dried at 40 ° C in a vacuum.

 ID ', 504

Next, a p-type semiconductor solution was spin-coated. A solution of 0.12 M Spiro-MeOTAD (Merck) and 20 mM LiN (SO ₂ CF ₃ ) 2 (Aldrich) in chlorobenzene was applied, 125 μL of this solution was applied to the sample and allowed to act for 60 s The solution was spun off for 30 s at 2000 rmp and the sample stored overnight in the dark in air As stated above, this storage is believed to cause oxygen doping of the p-type semiconductor, thereby increasing the conductivity of the p-type semiconductor.

Finally, a metal back electrode was vacuum applied as a second electrode by thermal metal evaporation. Ag was used as metal which has been evaporated s at a rate of 3 Å at a pressure of about 2 ^* 10 ^"6 mbar, so that a layer thickness of about 200 nm was formed.

After preparation, the cell was stored for 2 days in dry air (8% relative humidity).

To determine the efficiency, the respective current / voltage characteristic was measured with a Source Meter Model 2400 (Keithley Instruments Inc.) under irradiation with a xenon solar simulator (LOT-Oriei 300 W AM 1.5) two days after production. The initial measurement was carried out with unencapsulated cells. A power Voltage characteristic of the comparison sample measured after two days is shown in FIG. The comparative sample had the characteristics listed in Table 1.

 Table 1: Characteristics comparative sample without doping.

The short-circuit current isc (ie the current density at zero load resistance) was 9.29 mA / cm ² , the open-terminal voltage Voc (ie the load at which the current density has dropped to zero) was 860 mV, the filling factor FF was 55% and the ETA was 4.4%.

Example 1: Doping with 5 mM AG-TFSI

As a first exemplary embodiment of a photovoltaic element 110 according to the invention, the comparison sample described above was modified by doping the p-type semiconductor 126 or its matrix material 128 with silver bis (trifluoromethylsulfonyl) imide (Ag-TFSI). For this purpose, the p-type semiconductor solution of 0.12 M Spiro-MeOTAD (source Merck) and 20 mM LiNB02CF3) 2 (source Aldrich) in chlorobenzene 5 mM silver bis (trifluoromethylsulfonyl) imide (source Aldrich) in cyclohexanone added. This solution was then spun onto the sample as described in the comparative sample.

The metal back electrode as the second electrode 132 was immediately vacuum deposited by thermal metal evaporation. The metal used was Ag, which was evaporated at a rate of 3 Å / s at a pressure of about 2 × 10 ^-6 mbar to give a film thickness of about 200 nm.

To determine the efficiency η, the respective current / voltage characteristic was measured with a Source Meter Model 2400 (Keithley Instruments Inc.) under irradiation with a xenon solar simulator (LOT-Oriel 300 W AM 1.5) immediately and 2 days after production. The initial measurement was carried out with unencapsulated cells.

Current-voltage characteristics with 5 mM silver bts- (trifluoromethylsulfonyl) imide are shown in FIG. The characteristics of the comparative sample and the sample according to Example 1 are shown in Table 2.

IscjjnA / cm ² ] Voc [mV] FF [%] ETA [%] without Ag-TFSI, t = 0 4.13 760 26 0.8

 without Ag-TFSI, t = 2 days 9.29 860 55 4.4

with Ag-TFSI, t = 0 9.20 800 69 5.1 with Ag-TFSI, t = 2 days 9.80 780 66 5.0

Table 2: Comparison of characteristic data of an undoped comparative sample and a sample according to Example 1 at different measurement times.

Example 2: Variation of the dopant concentration

In order to investigate the influence of the amount of dopant on the properties of the photovoltaic element 110, variations of Example 1 with 1-20 mM Si-bis-bis (trifluoromethylsulfonyl) imide were further prepared. Otherwise, the samples were prepared as the sample according to Example 1 described above. The characteristics of these samples, measured after 2 days, are shown in Table 3. The illumination in these measurements was once again 100 Sun, as in the above measurements.

Table 3: Comparison of characteristic data of samples according to Example 2 with different Ag-TFSI content.

The measurements show that the efficiency at about 10 mM Ag-TFSI a maximum of about 5.1% occurs. Overall, however, the efficiency between 3 mM and 20 mM follows a comparatively flat course, which may represent a technical advantage in terms of production.

Example 3 Variation of the Matrix Material Furthermore, the influence of the matrix material 128 on the properties of the photovoltaic elements 110 was investigated as example 3. For this purpose, samples were prepared according to Example 1 described above, but Spiro-MeOTAD was replaced as matrix material 128 by different matrix materials 128 with different concentrations, in particular by the above-mentioned matrix materials of the type ID522, ID322 and ID367. In order to introduce silver 130 in oxidized form, 10 m of silver bis (trifluoromethylsulfonyl) imide were again used as dopant in each of the samples. The characteristics of the samples thus obtained are shown in Table 4. The indicated concentrations of 160 mg / ml and 200 mg / ml relate to the concentration of the matrix material 28 in the liquid phase. The characteristics were again recorded after 2 days and measured at 00 Sun [mW / cm ² ]. p-Conductor Comment lsc [mA / cm ² ] VocfmV] FF [%] ETA [%]

ID522 Conc. 160mg / ml, 10mM AgTFSI -6.22 740 73 3.4

ID522 conc. 200mg / ml, 10 mMAgTFSI -7.07 740 70 3.7

ID322 Conc. 160mg / ml, 10mM AgTFSI -1.68 500 40 0.3

1D322 conc. 200mg / ml, 10mMAgTFSI -1 .49 580 39 0.3

ID367 conc. 160mg ml, 10mM AgTFSI -6.89 760 73 3.8

ID367 Conc. 200mg / ml, 10 mMAgTFSI -7.14 740 71 3.7

Table 4: Comparison of characteristic data of samples according to Example 4 with different

 Matrix materials.

Example 4: Variation of the dopant

Furthermore, tests were carried out in which silver 130 was introduced in oxidized form by means of other dopants in the matrix material 128. In addition, in AgTFSI, silver has been replaced by other groups to check whether the doping effect and its positive effect on the characteristics of the photovoltaic devices 110 may be caused by TFSI instead of the silver 130 in oxidized form.

For this purpose, 4 different samples were prepared in Example 4, which again agree with Example 1 above except for the dopant. However, instead of Ag-TFSI, salts other than dopants each in an amount of 20 mM were added. The results are shown in Table 5. Ag nitrate was added as a solid in the p-conductor solution.

Table 5: Comparison of characteristics of samples according to Example 5 with different

 Dopants.

The results show that TFSl generally leads to high efficiencies only as an anion in a silica salt. In addition to Ag-TFSI, however, other silver salts show comparatively high efficiencies, in particular silver nitrate and oversize triflate. In general, compounds, in particular salts, can be used as dopant, which Silver in oxidized form, in particular silver (I) salts of the formula [Ag ⁺ ] _m [A ^m -], particularly preferably Ag-TFSI, silver nitrate and silver triflate.

Finally, synthetic examples of low molecular weight organic p-type semiconductors are listed below, which, individually or in combination, can be used in the context of the present invention and which, for example, can fulfill formula I above. Synthesis Examples:

(A) General Synthetic Schemes for the Preparation of Compounds of Formula I:

(a) Synthesis Route I:

(a 1) Synthesis Step l-R 1:

I-R1

The synthesis in synthesis step I-R1 was carried out on the basis of the following references: a) Liu, Yunqi; a, Hong; Jen, Alex KY .; CHCOFS; Chem, Commun .; 24; 1998; 2747-2748, b) Goodson, Felix E .; Hauck, Sheila; Hartwig, John F .; J. Am. Chem. Soc. 121; 33; 1999; 7527-7539, c) Shen, Jiun Yi; Lee, Chung Ying; Huang, Tai-Hsiang; Lin, Jiann T .; Tao, Yu Tai; Chien, Chin-Hsiung; Tsai, Chiitang; J. Mater. Chem .; 15; 25; 2005; 2455 - 2463, d) Huang, Ping-Hsin; Shen, Jiun-yi; Pu, Shin-chien; Wen, Yuh Sheng; Lin, Jiann T .; Chou, Pi-Tai; Yeh, Ming-Chang P .; J. Mater. Chem .; 16; 9; 2006; 850-857, e) Hirata, Narukuni; Kroeze, Jessica E .; Park, Taiho; Jones, David; Haque, Saif A .; Holmes, Andrew B .; Durrant, James R .; Chem. Commun .; 5; 2006; 535 - 537.

(a2) Synthesis Step I-R2:

The synthesis in synthesis step I-R2 was carried out on the basis of the following references: a) Huang, Qinglan; Evmenenko, Guennadi; Dutta, Pulak; Marks, Tobin J .; J. Am. Chem. Soc. 125; 48; 2003; 14704 - 14705, b) Bacher, Erwin; Bayerl, Michael; Rudati, Paula; Reckefuss, Nina; Mueller, C. David; Meerholz, Klaus; Nuyken, Oskar; Macromolecules; EN; 38; 5; 2005; 1640-1647, c) Li, Zhong Hui; Wong, Man Shing; Tao, Ye; D'Loro, Marie; J. Org. Chem. EN; 69; 3; 2004; 921 - 927.

(a3) Synthesis Step I-R3:

The synthesis in synthesis step I-R3 was carried out on the basis of the following reference:

J. Grazuleviciüs; J. of Photochem. and Photobio., A: Chemistry 2004 162 (2-3), 249-252,

The compounds of the formula I can be prepared via the sequence of the synthesis steps of the synthesis route I shown above. The coupling of the reactants in steps (I-R1) to (I-R3) can be carried out, for example, by Ullmann reaction with copper as catalyst or under palladium catalysis. (b) Synthetic Route II:

(b 1) Synthesis Step II-R1:

 The synthesis in synthesis step II-R1 was carried out in accordance with the references listed under I-R2.

(b2) Synthesis Step l / ~ R2:

The synthesis in synthesis step II-R2 was carried out on the basis of the following references: a) Bacher, Erwin; Bayerl, Michael; Rudati, Paula; Reckefuss, Nina; Müller, C. David; Meerholz, Klaus; Nuyken, Oskar; Macromolecules; 38; 5; 2005; 1640-1647, b) Goodson, Felix E .; Hauck, Sheila; Hartwig, John F .; J. Am. Chem. Soc. 121; 33; 1999; 7527-7539; Hauck, Sheila I .; Lakshmi, KV; Hartwig, John F .; Org. Lett .; 1 ; 13; 1999; 2057-2060. (B3) Synthesis Step H-R3:

The compounds of the formula I can be prepared via the sequence of the synthesis steps of the synthesis route II shown above. The coupling of the reactants in the steps (II-R1) to (II-R3), as well as under Synthesis Route I, for example, by Ullmann reaction with copper as catalyst or under palladium catalysis. (c) Preparation of the starting amines:

If the diarylamines are not commercially available in the synthesis steps I-R2 and II-R1 of the synthesis routes I and II, they can be prepared, for example, by Ullmann reaction with copper as catalyst or under palladium catalysis in accordance with the following reaction:

The synthesis was carried out in accordance with the following overview:

Palladium-catalyzed C-N coupling reactions:

a) Yang, Buchwald; J. Organomet. Chem. 1999, 576 (1-2), 125-146, b) Wolfe, Marcoux, Buchwald; Acc. Chem. Res. 1998, 31, 805-818, c) Hartwig; Angew. Chem. Int. Ed. Engl. 1998, 37, 2046-2067. Copper-catalyzed C-N coupling reactions:

a) Goodbrand, Hu; Org. Chem. 1999, 64, 670-674, b) Lindley; Tetrahedron 1984, 40, 1433-1456.

(B) Synthesis Example 1: Synthesis of Compound ID367 (Synthetic Route I) (B1): Synthesis Step According to General Synthetic Scheme I-R1:

A mixture of 4,4'-dibromobiphenyl (93.6 g, 300 mmol), 4-methoxyaniline (133 g, 1.08 mol), Pd (dppf) Cl ₂ (Pd (1,1'-bis (diphenylphosphino) ferrocene) Cl2, 21, 93 g, 30 mmol), and t-BuONa (sodium tert-butoxide, 109.06 g, 1.136 mol) in toluene (1500 mL) was stirred under a nitrogen atmosphere at 110 ° C for 24 hours , After cooling the mixture was diluted with diethyl ether and filtered through a pad of Celite® (Carl Roth). The filter bed was washed with 1500 ml each of ethyl acetate, methanol and methylene chloride. The product was obtained as a tan solid (36 g, yield: 30%). HNMR (400 MHz, DMSO): δ 7.81 (s, 2H), 7.34-7.32 (m, 4H), 6.99-6.97 (m, 4H), 6.90-6, 88 (m, 4H), 6.81-6.79 (m, 4H), 3.64 (s, 6H).

(B2): Synthesis step according to general synthetic scheme I-R2:

Nitrogen was bubbled through a solution of dppf (1,1'-bis (diphenylphosphino) ferrocene, 0.19 g, 0.34 mmol) and Pd2 (dba) 3 (tris (dibenzylideneacetone) dipalladium (O) for 10 minutes). 0.15 g, 0.17 mmol) in toluene (220 ml). Then, t-BuONa (2.8 g, 29 mmol) was added and the reaction mixture was stirred for an additional 15 minutes. Successively 4,4'-dibromobiphenyl (25 g, 80 mmol) and 4,4'-dimethoxydiphenylamine (5.52 g, 20 mmol) were then added. The reaction mixture was heated for 7 hours at a temperature of 100 ° C under a nitrogen atmosphere. After cooling to room temperature, the reaction mixture was quenched with ice-water, the precipitate filtered off and dissolved in ethyl acetate. The organic layer was washed with water, dried over sodium sulfate and purified by column chromatography (eluent: 5% ethyl acetate / hexane). A slightly yellow colored solid was obtained (7.58 g, yield: 82%). HNMR (300 MHz, DMSO-d ₆ ): 7.60-7.49 (m, 6H), 7.07-7.04 (m, 4H), 6.94-6.91 (m, 4H), 6.83-6.80 (d, 2H), 3.75 (s, 6H). (B3): Synthesis step according to general synthetic scheme I-R3:

^ .N ^ -Bisf ^ methoxypheny ^ biphenyl ^^ '- diamine (product from Synthesis Step I-R1, 0.4 g, 1.0 mmol) and product from Synthesis Step I-R2 (1.0 g, 2.2 mmol ) were added under nitrogen atmosphere to a solution of t-BuONa (0.32 g, 3.3 mmol) in o-xylene (25 mL). Then, palladium acetate (0.03 g, 0.14 mmol) and a solution of 10 wt% P (t-Bu) 3 (tris-t-butylphosphine) in hexane (0.3 mL, 0.1 mmol) were added. added to the reaction mixture and stirred for 7 hours at 125 ^' C. Thereafter, the reaction mixture was diluted with 150 ml of toluene, filtered through Celite® and the organic layer was dried over Na ₂ SC <4. The solvent was removed and the crude product was reprecipitated three times from a mixture of tetrahydrofuran (THF) / methanol. The solid was purified by column chromatography (eluent: 20% ethyl acetate / hexane) followed by precipitation with THF / methanol and charcoal purification. After removal of the solvent, the product was obtained as a pale yellow solid (1, 0g, yield: 86%).

¹ HNMR (400 MHz, DMSO-d ₆ ): 7.52-7.40 (m, 8H), 6.88-7.10 (m, 32H), 6.79-6.81 (d, 4H) , 3.75 (s, 6H), 3.73 (s, 12H).

(C) Synthesis Example 2: Synthesis of Compound ID447 (Synthesis Route II)

(C1) Synthesis Step According to General Synthetic Scheme II-R2:

p-Anisidine (5.7 g, 46.1 mmol), t-BuONa (5.5 g, 57.7 mol) and P (t-Bu) ₃ (0.62 mL, 0.31 mmol) became of a solution of the product from Synthesis Step I-R2 (17.7 g, 38.4 mmol) in toluene (150 mL). After nitrogen for 20 minutes through the Pd2 (dba) 3 (0.35 g, 0.38 mmol) was added. The resulting reaction mixture was allowed to stir at room temperature for 16 hours under a nitrogen atmosphere. It was then diluted with ethyl acetate and filtered through Celite®. The filtrate was washed twice with 150 ml each of water and saturated brine. Drying of the organic phase over Na ₂ SO ₄ and removal of the solvent gave a black solid. This was purified by column chromatography (eluent: 0-25% ethyl acetate / hexane). An orange solid was obtained (14 g, yield: 75%). ¹ HNMR (300 MHz, DMSO): 7.91 (s, 1H), 7.43-7.40 (d, 4H), 7.08-6.81 (m, 16H), 3.74 (s , 6H), 3.72 (s, 3H).

(C2) Synthesis step according to general synthesis scheme II-R3:

t-BuONa (686 mg, 7.14 mmol) was heated at 100 ° C under vacuum, then the reaction was rinsed with nitrogen and allowed to cool to room temperature. Then, 2,7-dibromo-9,9-dimethylfluorene (420 mg, 1.19 mmol), toluene (40 mL) and Pd [P ('Bu) 3] 2 (20 mg, 0.0714 mmol) were added and the reaction mixture stirred at room temperature for 15 minutes. Subsequently, Ν, Ν, Ν'-ρ-trimethoxy-triphenylbenzidine (1, 5 g, 1.27 mmol) was added to the reaction mixture and stirred at 120 ° C for 5 hours. The mixture was filtered through a Celite® / MgS0 ₄ mixture and washed with toluene. The crude product was purified by column chromatography (eluent: 30% ethyl acetate / hexane) twice, and after dropping twice from THF / methanol to give a pale yellow solid (200 mg, yield: 13%). H NMR: (400 MHz, DMSO-de): 7.60-7.37 (m, 8H), 7.02-6.99 (m, 16H), 6.92-6.87 (m, 20H) , 6.80-6.77 (d, 2H), 3.73 (s, 6H), 3.71 (s, 12H), 1, 25 (s, 6H)

(D) Synthesis Example 3: Synthesis of Compound ID453 (Synthesis Route [)

(D 1) Preparation of the starting amine:

Step 1 :

NaOH (78 g, 4 eq) was added to a mixture of 2-bromo-9H-fluorene (120 g, 1 eq) and BnEtsNCI (benzyltriethylammonium chloride, 5.9 g, 0.06 eq) in 580 ml of DMSO (dimethyisulfoxide). given. The mixture was cooled with ice water and methyl iodide (Mel) (160 g, 2.3 eq) was slowly added dropwise. The reaction mixture was allowed to stir overnight, then poured into water and then extracted three times with ethyl acetate. The combined organic phases were washed with brine, dried over Na ₂ SO ₄ and the solvent removed. The crude product was purified by column chromatography on silica gel (eluent: petroleum ether). After washing with methanol the product was obtained (2-bromo-9,9 ^{I-dimethyl-9H-fluorene)} as a white solid (102 g). HNMR (400 MHz, CDCl3): δ 1, 46 (s, 6H), 7.32 (m, 2H), 7.43 (m, 2H), 7.55 (m, 2H), 7 , 68 (m, 1H)

Step 2:

p-Anisidine (1.23 g, 10.0 mmol) and 2-bromo-9,9'-dimethyl-9H-fluorene (3.0 g, 11.10 mmol) were added under a nitrogen atmosphere to a solution of t -BuONa (1.44 g, 15.0 mmol) in 15 mL toluene (15 mL). Pd2 (dba) 3 (92 mg, 0.1 mmol) and a 10 wt% solution of P (t-Bu) 3 in hexane (0.24 ml, 0.08 mmol) were added and the reaction mixture at room temperature Stirred for 5 hours. The mixture was then quenched with ice water, the precipitate filtered off and dissolved in ethyl acetate. The organic phase was washed with water and dried over Na ₂ SO ₄ . After purification by column chromatography of the crude product (eluent: 10% ethyl acetate / hexane) gave a slightly yellow colored solid (1, 5 g, yield: 48%). HNMR (300 MHz, C ₆ D ₆ ): 7.59-7.55 (d, 1H), 7.53-7.50 (d, 1H), 7.27-7.22 (t, 2H , 7.19 (s, 1H), 6.99-6.95 (d, 2H), 6.84-6.77 (m, 4H), 4.99 (s, 1H), 3, 35 (s, 3H), 1, 37 (s, 6H).

(D2) Preparation of the Compound ID453 (D2.1) to be Used According to the Invention: Synthesis Step According to General Synthetic Scheme I-R2:

Product from a) (4.70 g, 10.0 mmol) and 4,4'-dibromobiphenyl (7.8 g, 25 mmol) were added to a solution of t-BuONa (1, 15 g, 12 mmol) in 50 mL Toluene added under nitrogen. Pd2 (dba) 3 (0.64 g, 0.7 mmol) and DPPF (0.78 g, 1.4 mmol) were added and the reaction mixture was allowed to stir at 100 X for 7 hours. After quenching the reaction mixture with ice-water, the precipitated solid was filtered off and dissolved in ethyl acetate. The organic phase was washed with water and dried over Na ₂ SO ₄ . After purification by column chromatography of the crude product (eluent: 1% ethyl acetate / hexane) gave a slightly yellow colored solid. (4.5 g, yield: 82%). HNMR (400 MHz, DMSO-d6): 7.70-7.72 (d, 2H), 7.54-7.58 (m, 6H), 7.47-7.48 (d, 1H), 7.21-7.32 (m, 3H), 7.09-7.12 (m, 2H), 6.94-6.99 (m, 4H), 3.76 (s, 3H), 1, 36 (s, 6H).

OMe N ⁴ , N ⁴ '- bis (4-methoxyphenyl) biphenyl-4,4'-diamine (0.60 g, 1.5 mmol) and product from the previous Synthetic Step I-R2 (1. 89 g; 5 mmol) were added under nitrogen to a solution of t-BuONa (0.48 g, 5.0 mmol) in 30 mL of o-xylene. Palladium acetate (0.04 g, 0.18 mmol) and P (t-Bu) 3 in a 10 wt% solution in hexane (0.62 mL, 0.21 mmol) were added and the reaction mixture for 6 h stirred at 25 ^° C. It was then diluted with 100 ml of toluene and filtered through Ceiite®. The organic phase was dried over Na ₂ SO ₄ and the solid obtained was purified by column chromatography (eluent: 10% ethyl acetate / hexane). It was reprecipitated from THF / methanol and gave a slightly yellow colored solid (1, 6 g, yield: 80%).

¹ HNMR (400 MHz, DMSO-de): 7.67-7.70 (d, 4H), 7.46-7.53 (m, 14H), 7.21-7.31 (m, 4H), 7.17-7.18 (d, 2H), 7.06-7.1 1 (m, 8H), 6.91-7.01 (m, 22H), 3.75 (s, 12H), 1 , 35 (s, 12H).

(E) Further compounds of the formula I to be used according to the invention:

The compounds listed below were obtained analogously to the previously described syntheses: (E1) Synthesis Example 4: Compound ID320

¹ HNMR (300 MHz, THF-ds): δ 7.43-7.46 (d, 4H), 7.18-7.23 (t, 4H), 7.00-7.08 (m, 16H) , 6.81-6.96 (m, 18H), 3.74 (s, 12H)

(E2) Synthesis Example 5: Compound ID321

¹ HNMR (300 MHz, THF-ds): 3 7.37-7.50 (t, 8H), 7.37-7.40 (d, 4H), 7.21-7.26 (d, 4H) , 6.96-7.12 (m, 22H), 6.90-6.93 (d, 4H), 6.81-6.84 (d, 8H), 3.74 (s, 12H)

(E3) Synthetic Example 6: Compound ID366

¹ HNMR (400 MHz, DMSO-d6): δ 7.60-7.70 (t, 4H), 7.40-7.55 (d, 2H), 7.17-7.29 (m, 8H) , 7.07-7.09 (t, 4H), 7.06 (s, 2H), 6.86-7.00 (m, 24H), 3.73 (s, 6H), 1, 31 (s , 12H)

HNMR (400 MHz, DMSO-d6): δ 7.48-7.55 (m, 8H), 7.42-7.46 (d, 4H), 7.33-7.28 (d, 4H), 6.98-7.06 (m, 20H), 6.88-6.94 (m, 8H), 6.78-6.84 (d, 4H), 3.73 (s, 12H), 1, 27 (s, 18H)

HNMR (400 MHz, THF-d8): δ 7.60-7.70 (t, 4H), 7.57-7.54 (d, 4H), 7.48-7.51 (d, 4H), 7.39-7.44 (t, 6H), 7.32-7.33 (d, 2H), 7.14-7.27 (m, 12H), 7.00-7.10 (m, 10H ), 6.90-6.96 (m, 4H), 6.80-6.87 (m, 8H), 3.75 (s, 12H), 1, 42 (s, 12H)

¹ HNMR (400 MHz, dmso-d ₆ ): δ 7.39-7.44 (m, 8H), 7.00-7.07 (m, 13H), 6.89-6.94 (m, 19H ), 6.79-6.81 (d, 4H), 3.73 (s, 18H)

(E7) Synthesis Example 10: Compound ID450

HNMR (400 MHz, dmso-d ₆ ): δ 7.55-7.57 (d, 2H), 7.39-7.45 (m, 8H), 6.99-7.04 (m, 15H) , 6.85-6.93 (m, 19H), 6.78-6.80 (d, 4H), 3.72 (s, 18H), 1, 68-1, 71 (m, 6H), 1 , 07 (m, 6H), 0.98-0.99 (m, 8H), 0.58 (m, 6H)

¹ HNMR (400 MHz, DMSO-d6): δ 7.38-7.44 (m, 8H), 7, 16-7.19 (d, 4H), 6.99-7.03 (m, 12H) , 6.85-6.92 (m, 20H), 6.77-6.79 (d, 4H), 3.74 (s, 18H), 2.00-2.25 (m, 4H), 1 , 25-1,50 (m, 6H)

(E9) Synthesis Example 12: Compound ID480

¹ HNMR (400 MHz, DMSO-d6): δ 7.40-7.42 (d, 4H), 7.02-7.05 (d, 4H), 6.96-6.99 (m, 28H) , 6.74-6.77 (d, 4H), 3.73 (s, 6H), 3.71 (s, 12H)

(E 10) Synthesis fog game 13: Connection ID518

HNMR (400 MHz, DMSOd6): 7.46-7.51 (m, 8H), 7.10-7.12 (d, 2H), 7.05-7.08 (d, 4H), 6.97 -7.00 (d, 8H), 6.86-6.95 (m, 20H), 6.69-6.72 (m, 2H), 3.74 (s, 6H), 3.72 (s , 12H), 1, 24 (t, 12H)

(E11) Synthetic Example 14: Compound ID519

¹ HN R (400 MHz, DMSO-d6): 7.44-7.53 (m, 12H), 6.84-7.1 (m, 32H), 6.74-6.77 (d, H) , 3.76 (s, 6H), 3.74 (s, 6H), 2.17 (s, 6H), 2.13 (s, 6H)

(E12) Synthesis Example 15: Compound ID521

HNMR (400 MHz, THF-de): 7.36-7.42 (m, 12H), 6.99-7.07 (m, 20H), 6.90-6.92 (d, 4H ), 6.81-6.84 (m, 8H), 6.66-6.69 (d, 4H), 3.74 (s, 12H), 3.36-3.38 (q, 8H), 1, 41-1, 17 (t, 12H)

¹ HNMR (400 MHz, DMSO-d ₆ ): 7.65 (s, 2H), 7.52-7.56 (t, 2H), 7.44-7.47 (t, 1H), 7.37-7.39 (d, 2H), 7.20-7.22 (m, 10H), 7.05-7.08 (dd, 2H), 6.86-6.94 ( m, 8H), 6.79-6.80-6.86 (m, 12H), 6.68-6.73, (dd, 8H), 6.60-6.62 (d, 4 H), 3.68 (s, 12H), 3.62 (s, 6H)

(E) Synthesis Example 17: Compound ID523

¹ HNMR (400 MHz, THF-d ₈ ): 7.54-7.56 (d, 2H), 7.35-7.40 (dd, 8H), 7.18 (s, 2H) 7 , 00-7.08 (m, 18H), 6.90-6.92 (d, 4H), 6.81-6.86 (m, 12H), 3.75 (s, 6H) , 3.74 (s, 12H), 3.69 (s, 2H)

¹ HNMR (400 MHz, THF-d8): 7.97-8.00 (d, 2H), 7.86-7.89 (d, 2H), 7.73-7.76 (d, 2H), 7.28-7.47 (m, 20H), 7.03-7.08 (m, 16H), 6.78-6.90 (m, 12H), 3.93-3.99 (q, 4H ), 3.77 (s, 6H), 1, 32-1, 36 (s, 6H)

E 16) Synthesis Example 19: Compound ID568

HNMR {400 MHz, DMSO-d6): 7.41-7.51 (m, 12H), 6.78-7.06 (m, 36H), 3.82-3.84 (d, H), 3 , 79 (s, 12H), 1, 60-1, 80 (m, 2H), 0.60-1, 60 (m, 28H)

(E17) Synthesis Example 20: Compound ID569

HNMR (400 MHz, DMSO-d6): 7.40-7.70 (m, 10H), 6.80-7.20 (m, 36H), 3.92-3.93 (d, H), 2 , 81 (s, 12H), 0.60-1, 90 (m, 56H) (E18) Synthesis Example 21: Compound ID572

¹ HNMR (400 MHz, THF-d8): 7.39-7.47 (m, 12H), 7.03-7.11 (m, 20H), 6.39-6.99 (m, 8H), 6.83-6.90 (m, 8H), 3.78 (s, 6H), 3.76 (s, 6H), 2.27 (s, 6H)

(E19) Synthesis Example 22: Compound ID573

¹ HNMR (400 MHz, THF-d8): 7.43-7.51 (m, 20H), 7.05-7.12 (m, 24H), 6.87-6.95 (m, 12H), 3.79 (s, 6H), 3.78 (s, 12H)

E20) Synthesis Example 23: Compound ID575

¹ HNMR (400 MHz, DMSO-d6): 7.35-7.55 (m, 8H), 7.15-7.45 (m, 4H), 6.85-7.10 (m, 26H), 6.75-6.85 (d, 4H), 6.50-6.60 (d, 2H), 3.76 (s, 6H), 3.74 (s, 12H)

(E21) Synthesis Example 24: Compound ID629

HNMR (400 MHz, THF-d ₈ ): 7.50-7.56 (dd, 8H), 7.38-7.41 (dd, 4H), 7.12-7.16 (d, 8 H) 7.02-7.04 (dd, 8H), 6.91-6.93 (d, 4H), 6.82-6.84 (dd, 8H), 6.65-6, 68 (d, 4H) 3.87 (s, 6H), 3.74 (s, 12H)

(E22) Synthesis Example 25: Compound ID631

1HNMR (400 MHz, THF-de): 7.52 (d, 2H), 7.43-7.47 (dd, 2H), 7.34-7.38 (m, 8H), 7, 12-7.14 (d, 2H), 6.99-7.03 (m, 12H), 6.81-6.92 (m, 20H), 3.74 (s, 18H), 2.10 (s, 6H)

(F) Synthesis of Compounds of Formula IV:

(a) Coupling of p-anisidine and 2-bromo-9,9-dimethyl-9H-fluorene

To 0.24 ml (0.08 mmol) of P (t-Bu) ₃ (d = 0.68 g / ml) and 0.1 g of Pd ₂ (dba) ₂ [= (tris (dibenzylideneacetone) dipalladium (0)] ( 0.1 mmol) was added 10 mL to 15 mL toluene (anhydrous, 99.8%) and the mixture was stirred at room temperature for 10 min 1.44 g (15 mmol) sodium tert-butoxide (97.0%) was added and the The mixture was stirred for a further 15 minutes at room temperature, then 2.73 g (11 mmol) of 2-bromo-9,9-dimethyl-9H-fluorene were added and the reaction mixture was stirred for an additional 15 minutes mmol) of p-anisidine was added and the mixture was stirred for 4 h at 90 ° C.

The reaction mixture was mixed with water and the product was precipitated from hexane. The aqueous phase was further extracted with ethyl acetate. The organic phase and the precipitated and filtered precipitate were combined and purified by column chromatography on SiC ^ phase (hexane: ethyl acetate 10: 1).

There were obtained 1.5 g (yield: 47.6%) of a yellow solid.

¹ HNMR (300 MHz, C6D6): 6.7-7.6 (m, 11H), 5.00 (s, 1H,), 3.35 (s, 3H), 1.37 (s, 6H)

(b) coupling the product of (a) with tris (4-bromophenyl) amine

To 0.2 mL (0.07 mmol) of P (t-Bu) ₃ (D = 0.68 g / mL) and 0.02 g (0.1 mmol) of palladium acetate was added 25 mL of toluene (anhydrous) and the mixture 10 Stirred at room temperature for min. 0.4 g (1.2 mmol) of sodium t-butoxide (97.0%) was added and the mixture was stirred at room temperature for an additional 15 minutes. Subsequently, 0.63 g (1.3 mmol) of tris (4-bromophenyl) amine was added and the reaction mixture for further Stirred for 15 min. Finally, 1.3 g (1.4 mmol) of the product from step (a) were added and the mixture was stirred for 5 h at 90 ° C.

The reaction mixture was mixed with ice-cold water and extracted with ethyl acetate. The product was precipitated from a mixture of hexane / ethyl acetate and purified by column chromatography on SiO 2 phase (hexane: ethyl acetate gradient 9: 1 → 5: 1).

There was obtained 0.7 g (yield: 45%) of a yellow product. HNMR (300 MHz, C6D6): 6.6-7.6 (m, 45H), 3.28 (s, 9H), 1.26 (s, 18H)

(G) Synthesis of Compounds ID504:

The preparation was carried out starting from (4-bromo-phenyl) -bis (9,9-dimethyl-9H-fluoren-2-yl); (see Chemical Communications, 2004, 68-69); which first with

^4,4,5,5,4, 4 ', 5', 5'-octamethyl [2,2 '] bi [[1, 3,2] dioxaboro! Anyl] was reacted (step a). This was followed by coupling with 9Br-DIPP-PDCI (step b). This is followed by saponification to the anhydride (step c) and subsequent reaction with glycine to form the end compound (step d).

Step a:

A mixture of 30g (54mmol) (4-bromophenyl) bis (9,9-dimethyl-9H-fluoren-2-yl), 41g (162mmol) 4,4,5,5,4 ', 4' , 5 ', 5'-Octamethyl- [2,2 ^, ] bi [[1,3 _J 2] dioxaborolanyl], 1g (1,4mmol) Pd (dpf) ₂ Cl ₂ , 15,9g (162mmol) potassium acetate and 300mL Dioxane was heated to 80 ° C and stirred for 36h. After cooling, the solvent was removed and the residue was dried at 50 ° C in a vacuum oven.

Purification was carried out by filtration through silica gel with the eluent n-hexane: dichloromethane 1: 1. After separation of the educt, the eluent was converted to dichloromethane. The product was isolated as a reddish and sticky residue. This was stirred at RT for 0.5 h with methanol. The light precipitate was filtered off. After drying at 45 ° C in a vacuum oven, 24 g of a light solid was obtained, which corresponds to a yield of 74%.

Analytical data

¹ H-NMR (500 MHz, CD ₂ Cl _2, 25 ° C): δ = 7.66-7.61 (m, 6H); 7.41-7.4 (m, 2H); 7.33-7.25 (m, 6H); 7, 13-7, 12 (m, 2H); 7.09-7.07 (m, 2H); 1, 40 (s, 12H); 1, 32 (s, 12H)

Step b:

In 500mL dioxane, 17.8g (32mmol) of 9Br-DIPP-PDCI and 19mL (95mmol) of Smolare NaOH were added. This mixture was degassed with argon for 30 minutes. Then, 570 mg (1.1 mmol) of Pd [P (tBu) ₃ ] 2 and 23 g (38 mmol) of step a were added and stirred under argon at 85 ° C for 17 h.

Purification was carried out by column chromatography with the eluent

Dichloromethane: toluene 4: 1.

There were obtained 22.4 g of a purple solid, which corresponds to a yield of 74%.

Analytical data:

¹ H-NMR (500MHz, CH 2 Cl 2, 25 ° C): δ = 8.59-8.56 (m, 2H); 8.46-8.38 (m, 4H); 8.21-8, 19 (d, 1H); 7.69-7.60 (m, 6H); 7.52-7.25 (m, 17H); 2.79-2.77 (m, 2H); 1, 44 (s, 12H); 1, 17-1, 15 (d, 12H) step e:

In 200 ml of 2-methyl-2-butanol, 22.4 g (23 mmol) of step b and 73 g (1.3 mol) of KOH were introduced and stirred at reflux for 17 h. After cooling, the reaction mixture was added to 1 L of ice-water + 50 mL of concentrated acetic acid. The orange-brown solid was filtered through a frit and washed with water. The solid was dissolved in dichloromethane and extracted with deionized water. To the organic phase 10mL of concentrated acetic acid was added and stirred at RT. The solvent was removed from the solution. The residue was stirred for 30 min at RT with methanol, filtered with suction through a frit and dried in a vacuum oven at 55 ° C.

This gave 17.5 g of a purple solid, which corresponds to a yield of 94%. The product was used untreated in the next step.

Step, d: In 350mL of N-methyl-pyrrolidone 17.5g (22mmoi) of stage c, 16.4g (220mmol) of glycine and 4g (22mmol) of zinc acetate were added and stirred at 130 ° C for 12h.

After cooling, the reaction mixture was added to 1 L of deionized water. The precipitate was filtered through a frit, washed with water and dried in a vacuum oven at 70 ° C.

Purification was carried out by means of column chromatography with the eluent

Dichloromethane: ethanol 3: 1 + 2% triethylamine. The isolated product was stirred at 60 ° C with 50% acetic acid. The solid was filtered off with suction through a frit, washed with water and dried in a vacuum oven at 80 ° C.

It was 7.9 g of a purple solid, which corresponds to a yield of 42%.

Analytical data:

¹ H-NMR (500 MHz, THF, 25 ° C): δ = 8.37-8.34 (m, 2H); 8.25-8.18 (m, 4H); 8.12-8.10 (d, 1H); 7.74-7.70 (m, 4H); 7.59-7.53 (m, 4H); 7.45-7.43 (m, 4H); 7.39-7.37 (m, 2H); 7.32-7.22 (m, 6H); 4.82 (s, 2H); 1, 46 (s, 12H)

(H) Synthesis of Compounds ID662: l ° 662

ID662 was prepared by reaction of the corresponding commercially available

Hydroxyamic acid [2- (4-butoxyphenyl) -N-hydroxyacetamide] with sodium hydroxide.

LIST OF REFERENCE NUMBERS

110 photovoltaic element

 112 dye solar cell

 114 substrate

 116 first electrode

 118 Biockierschicht

 120 n-semiconducting material

 122 dye

 124 carrier element

 126 p-type semiconductor

 128 matrix material

 130 silver in oxidized form

 132 second electrode

 134 layer structure

 136 encapsulation

 138 Fermi level

 140 HOMO

 142 LUMO

 144 characteristic comparison without

 Silver in oxidized form, t = 0

 146 Characteristic comparison sample without

 Silver in oxidized form, t = 2 days

 148 Characteristic Sample Example 1, t = 0

 150 characteristic sample example,

 t = 2 days

Claims

claims

Photovoltaic element (110) for converting electromagnetic radiation into electrical energy, in particular dye solar cell (1 12), wherein the photovoltaic element (110) at least one first electrode (116), at least one n-semiconducting

Metal oxide (120), at least one electromagnetic radiation absorbing dye (122), at least one solid organic p-type semiconductor (126) and at least one second electrode (132), wherein the p-type semiconductor (126) comprises silver in oxidized form having.

The photovoltaic element (110) of claim 1, wherein the p-type semiconductor is derivable or prepared by depositing at least one p-type organic material (128) and silver in oxidized form on at least one support element, wherein the silver is preferably in the form of at least a silver (I) salt [Ag ⁺ ] _m [A ^m ], where A ^{m ~ is} the anion of an organic or inorganic acid, and m is an integer in the range of 1 to 3, preferably wherein m is 1.

3. A photovoltaic element (110) according to claim 2, wherein silver is applied in the form of at least one silver (l) salt [Ag ⁺ ] _m [A ^m -], wherein [A ^m -] see an anion of an organic Acid, preferably wherein the organic acid has at least one fluoro group -F or cyano group.

4. A photovoltaic element (110) according to claim 3, wherein [A ^{m ~} ] has a structure of the formula (II),

 O

R ^a -SX

Ö (il) wherein R ^{a is} a fluorine group -F or a, at least substituted with a fluorine group or a cyano group, alkyl radical, cycloalkyl radical, Ary! Rest or heteroaryl radical, and wherein X is -O- or N ^" -R ^b , and wherein R ^b comprises a fluoro group -F or a cyano group, and wherein R ^b further comprises a group of the formula -S (O) 2-.

The photovoltaic element (110) of claim 4, wherein R ^{a is} selected from the group consisting of -F, -CF ₃ , -CF ₂ -CF ₃ and -CH 2 -CN.

The photovoltaic element (110) of claim 4 or 5, wherein X- ^" -R j _S t, and wherein R ^{b is} selected from the group consisting of -S (O) 2-F, -S (O) ₂ - CF3, -S (0) ₂ - CF2-CF3 and -S (0) ₂ -CH ₂ -CN.

The photovoltaic element (110) according to any one of claims 3 to 5, wherein [A ^m -] is selected from the group consisting of bis (trifluoromethylsulfonyl) imide (TFSI), bis (trifluoroethylsulfonyl) imide, bis (fiuorosulfonyl) imide and trifluoromethylsulfonate where [A ^m ] is bis (trifluoromethylsulfonyl) imide (TFSI-).

The photovoltaic element (1 10) according to claim 3, wherein [A ^m -] is a trifluoroacetate group.

The photovoltaic element (1 10) according to claim 3, wherein [A ^m -] NO 3 ^" .

10. A photovoltaic element (1 10) according to any one of claims 3 to 8, wherein the p-type semiconductor is prepared or prepared by applying at least one p-type organic material (128) and at least one silver (l) salt [Ag ⁺ ] _m [A ^m -] on at least one support element, wherein the deposition by deposition from a liquid phase, the at least one p-type organic material and the at least one silver (l) salt [Ag ⁺ ] _m [A ^m ] takes place.

11. A photovoltaic element (110) according to claim 10, wherein the liquid phase further comprises at least one solvent, in particular an organic solvent, in particular a solvent selected from: cyclohexanone; Chlorobenzene; benzofuran; Cyclopentanone.

12. Photovoltaic element (1 10) according to the preceding claim, wherein at least Ag ⁺ and preferably also the anionic compound [A ^{m ~} ] in the matrix material (128) is distributed substantially uniformly.

13. The photovoltaic element (110) according to one of the two preceding claims, wherein the matrix material (128) comprises at least one low molecular weight organic p-type semiconductor (126).

14. A photovoltaic element (110) according to any one of claims 2 to 1 1, wherein the p-type organic material (128) is a spiro compound, in particular spiro-MeGTAD, and / or a compound having the structural formula: includes, where

A ¹ , A ² , A ³ , independently of one another, are optionally substituted, aryl groups or heteroaryl groups,

R ¹ , R ² , R ^{3 are} independently selected from the group consisting of the substituents -R, -OR, -NR _2> -A -OR and -A ⁴ -NR _2l wherein R is selected from the group consisting of alkyl , Aryl and heteroryl, and wherein A ^{4 is} an aryl group or heteroaryl group, and wherein n is independently 0, 1, 2 or 3 for each occurrence in formula I, with the proviso that the sum of the individual values n is at least 2 and at least two of R \ R ² and R ^{3 are} -OR and / or -NR 2.

15. Photovoltaic element (1 10) according to one of the preceding claims, further comprising at least one encapsulation, wherein the encapsulation is arranged to the photovoltaic element (1 10), in particular the electrodes (116, 132) and / or the p-type semiconductor (126), to shield against an ambient atmosphere.

16. A photovoltaic element (1 10) according to claim 10 or 1 1, wherein the liquid phase, the at least one silver (l) salt [Ag ⁺ ] _m [A ^m -] in a concentration of 0.5 mM / ml to 50 mM / ml, more preferably in a concentration of 1 mM / ml up to 20 mM / ml.

17. A process for producing a solid organic p-type semiconductor (126) for use in an organic component, in particular a photovoltaic element (1 10) according to any one of the preceding claims, wherein at least one p-type organic matrix material (128) and at least silver in oxidized form, preferably at least one silver (I) salt [Ag ^ A ™ -], be applied from at least one liquid phase to at least one support element, wherein [A] - is the anion of an organic or inorganic acid, and wherein the compound [Ag ⁺ ] _m [A ^m ] is preferably AgNO 3 or silver bis (trifluoromethylsulfonyI) imide.

18. The method according to the preceding claim, wherein the liquid phase further comprises at least one solvent, in particular an organic solvent, in particular a solvent selected from: cyclohexanone; Chlorobenzene; benzofuran; Cyclopentanone.

19. The method according to any one of the preceding method claims, wherein the method is carried out at least partially in an oxygen-poor atmosphere.

20. A method for producing a photovoltaic element (110), in particular according to one of the preceding claims, a photovoltaic element (10), wherein in the method at least one first electrode (116), at least one n-semiconductive metal oxide (120 ), at least one electromagnetic radiation absorbing dye (122), at least one solid organic p-type semiconductor (126), and at least one second electrode (132) are provided, wherein the p-type semiconductor (126) is prepared by a method according to any one of previous method claims.