WO2017178674A1

WO2017178674A1 - Organic hole transport materials containing an ionic liquid

Info

Publication number: WO2017178674A1
Application number: PCT/ES2017/070168
Authority: WO
Inventors: Laura CALIÓ; Manuel SALADO MANZORRO; Samrana KAZIM; Shahzada Ahmad
Original assignee: Abengoa Research, S.L.
Priority date: 2016-04-11
Filing date: 2017-03-22
Publication date: 2017-10-19
Also published as: ES2641860A1; ES2641860B1

Abstract

The present invention relates to hole transport compositions containing an organic charge transport material and a salt containing an organic cation. Preferably, the hole transport composition comprises an ionic liquid. The ionic liquid efficiently dopes the organic hole transport material. In a particular embodiment, the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP TFSI) is used as a dopant or additive. The invention also relates to optoelectronic and/or electrochemical devices containing the hole transport composition, particularly perovskite-based solar cells.

Description

Organic materials for transporting holes containing an ionic liquid

Technical field

The present invention relates to hollow transport compositions, electrochemical and / or optoelectronic devices, solar cells and the use of an ionic liquid as an additive and / or dopant of a cargo transport material.

State of the art

Recently, perovskite-based hybrid organo-lead solar cells have shown the best performance among solid-state hybrid solar cells. The hollow transport layer in perovskite solar cells represents one of the key components for achieving high power conversion efficiency (PCE). Currently, for the realization of the best solid-state devices, Spiro-OMeTAD (2,2 ', 7,7'-tetrakis (N, N-di-p-methoxyphenyl amine) -9,9-spirobifluorene) doped has It has been used as a material for transporting holes (HTM) for transporting holes from perovskite to the metal electrode. J. Burschka, N. Pellet, S.-J. Luna, R. Humphry-Baker, P. Gao, MK Nazeeruddin, M. Grátzel, Nature, 2013, 499, 316-319. However, Spiro-OMeTAD in its pure form is not very effective and very low yields and power conversion efficiency (PCE) are obtained, due to its low conductivity and mobility of the voids, as reported in U. Bach, D Lupo, P. COMT, JE Mose, F. Weissortel, J. Salbeck, H. Sprietzer, M. Grátzel, Nature, 1998, 395, 583. To overcome this obstacle, lithium salts (LiTFSI) (trifluoromethane) sulfonimide. and / or cobalt complexes were used as p-dopants to increase the concentration of the gaps. In addition, 4-tert-butylpyridine (t-BP) was used as an additive to suppress charge recombination, as described in JH Noh, NJ Jeon, YC Choi, MK Nazeeruddin, M. and S. GrátzelllSeok, J. Mater. Chem. A, 2013, 1, 11842-11847. See also J. Burschka, A. Dualeh, F. Kessler, E. Baranoff, N. -L. Cevey-Ha, C. Yi, MK Nazeeruddin, M. Grátzel, JAm Chem. Soc. 2011, 133, 18042-18045. The addition of highly hygroscopic lithium salts on the one hand improves the photovoltaic properties of the device, while on the other hand decreases its stability. The present invention attempts to provide other and / or different additives, which are effective in doping the organic void transport material used in these devices, but that do not have the disadvantages of LiTFSI, t-BP and cobalt complexes. It is therefore an objective to complement or dop the material for transporting holes with compounds that do not have the drawbacks mentioned above. In particular, it is an objective to avoid the detrimental effect of lithium-based salt on the stability of solar cells.

The present invention addresses the problems described above.

SUMMARY OF THE INVENTION

The present invention relates to new ionic liquids that efficiently allow doping cargo transport materials and, when used as an additive and / or dopant to an organic hollow transport material (HTM), effectively improve the transport characteristics loading of the material, while not affecting or even increasing the stability of optoelectronic devices, in particular sensitized solar cells.

In one aspect, the present invention provides a void transport composition comprising an organic cargo transport material and an ionic liquid comprising an A * cation, wherein A ⁺ is a substituted or unsubstituted heterocyclic ring of 5 or 6 members having 1-3 heteroatoms that are independently selected from N, S and O, with the proviso that at least one of the heteroatoms is a quaternary nitrogen atom.

In one aspect, the present invention provides an optoelectronic and / or electrochemical device, comprising the void transport composition of the invention.

In one aspect, the present invention provides the use of an ionic liquid as a dopant and / or additive to a cargo transport material and / or a perovskite.

In one aspect, the present invention provides the use of an ionic liquid as a dopant and / or additive to a cargo transport material for one or more selected from the group:

- doping a cargo transport material;

- increasing the mobility of cargo of a cargo transport material;

- increasing the conductivity of a cargo transport material; I - increasing the stability of cargo transport materials,

and in particular hollow transport materials (HTMs) and / or an optoelectronic device and / or electrochemical device comprising a load transport layer.

In one aspect, the present invention provides a solar cell, in particular a sensitizing dye and / or perovskite based on a solar cell, comprising the hollow transport composition of the invention. In one aspect, the present invention provides a solar cell based on perovskite oxide. In one embodiment, the solar cell is a solid state solar cell, preferably a hybrid solid state solar cell.

Brief description of the drawings:

Figure 1 shows the J-V curves of illuminated solar cells, in accordance with the embodiments of the invention compared to conventional devices. All devices contain Spiro-OMeTAD as HTM and different concentrations of BMP TFSI ionic liquid as a dopant, or LiTFSI and t-BP salt as conventional additives. One of the devices includes only the HTM and no additives at all.

Figure 2 shows the efficiency of conversion of incident photons into electrons (IPCE) of the same products as cited in Figure 1, with the exception of the device that does not contain any additives at all. Figure 3 shows the J-V curves of solar cells according to other aspects of the invention. In these devices, BMIM TFSI ionic liquid was compared as an additive with combinations of different ionic liquids in the void transport layer. Figure 4 shows the conversion efficiency curves of electron-incident photons (IPCE) for one of the devices cited in Figure 3.

Figure 5 shows the JV curve of a solar cell according to an aspect of the invention, which contains BMIM TFSI ionic liquid as a dopant. Figure 6 shows the normalized stability, measured for devices containing Spiro-OMeTAD as HTM and, or different concentrations of BMP TFSI ionic liquid as a dopant, or of conventional LiTFSI and t-BP additives. The devices were kept at room temperature outside the glove box, with a humidity around 45%. Devices containing ionic liquid (IL) are clearly more stable than the device containing conventional LiTFSI and t-BP additives.

Figure 7 is a schematic representation of a solar cell according to an aspect of the invention.

Figure 8 is a schematic representation of a solar cell according to another aspect of the invention. Detailed description of the main aspects

The present invention relates to additives and / or dopants of cargo transport materials and especially organic cargo transport materials. Preferably, the invention provides compositions and / or void transport materials. The invention relates to void transport compositions comprising organic cargo transport materials and additives. The additives are preferably ionic liquids and / or molten salts. Preferably, the molten salts and ionic liquids have hydrophobic properties.

In accordance with the invention, the ionic liquid comprises an A \ cation in which A is a 5 or 6-membered substituted or unsubstituted heterocyclic ring, having 1-3 heteroatoms, which are independently selected from N, S and O, with the proviso that at least one of the heteroatoms is a quaternary nitrogen atom. Said 5 or 6 membered heterocyclic ring may be further substituted by one or more substituents possibly present in said quaternary nitrogen atom.

In one aspect, said 5 or 6 member ring comprising a substituted nitrogen atom and optionally carbon atom substituents.

In one embodiment, cation A * is selected from the compounds of formulas (1) - (4) below:

where R ^ R ¹⁰ , R ₁ and R ₂ , as far as present, are independently selected from substituents comprising 1-30 carbon atoms and 0-20 heteroatoms provided that, in R ₁ and R ₂ , said Substituents are connected to the nitrogen atom by means of a simple CN bond. R ¹ -R ¹⁰ and R ₂ in the formula (2) can also be substituted by H. In addition to or in addition to the said 0-20 heteroatoms, any substituent can be, independently, partially or totally halogenated (Cl, Br, I, F), preferably fluorinated.

The term "independently", in this context, means any one or more of a group of substituents. such as R ^ R ¹⁰ , and R ₂ . they can be partially or totally halogenated, regardless of whether or not other substituents of the same group are halogenated.

Heteroatoms are preferably selected from N, P, S, O, Se, Te, B, and Si. Preferably, said substituents comprising 1-30 carbon atoms and 0-20 heteroatoms are substituents comprising 1-20 carbon atoms and 0-10 heteroatoms, preferably substituents comprising 1-15 carbon atoms and 0-5 heteroatoms, more preferably 1-10 carbon atoms and 0 heteroatoms. Optional halogens are not included in that number of 0-10 or 0-5 heteroatoms. In one embodiment, R ¹ -R ^1C , R, and R ₂ , as far as present, are independently selected from C1-C30 hydrocarbons, which may be partially and / or fully halogenated, and which may be substituted by one or more selected from the alkoxy, thioalkyl groups. -CN and / or -N0 ₂ , while R ¹ -R ¹⁰ and optionally R ₂ of the formula (2) can also be substituted by H. In one embodiment, said C1-C30 hydrocarbons are partially or fully fluorinated. In one embodiment, R ¹ -R ^1C , R, and R ₂ . to the extent herein, they are independently selected from C1-C20. preferably C1-C12 with aliphatic and / or aromatic substituents, which can be totally or partially halogenated, preferably fluorinated, and in which R ¹ -R ¹⁰ and optionally R ₂ in the formula (2) can also be substituted by H.

If a substituent is aromatic, it preferably has at least 6 carbons or 4-5 carbons and one or two heteroatoms of N, O and / or S. In one embodiment, R ^ and R ₂ , as far as present, are selected independently between alkyl, alkenyl, alkynyl or aryl which are substituted or unsubstituted, wherein said alkyl, alkenyl, alkynyl or aryl can be, independently, partially or totally halogenated, for example fluorinate. R ₂ in formula (2) can also be selected from H. R ¹ .R ¹⁰ , to the extent present, are independently selected from H and from alkyl, alkenyl. alkynyl or aryl which are substituted or unsubstituted, wherein said alkyl, alkenyl, alkynyl or aryl can be, independently, partially or totally halogenated. In one embodiment, the compounds with formula (1) - (4) comprise at least one alkyl to one of R ¹ -R ¹⁰ which are present in the compound, while the others of said R ^ R ¹⁰ , in the to the extent possible, they may be H. Said alkyls may be partially or totally halogenated. In one embodiment, R ¹ -R ¹⁰ , to the extent present, are all H, or in the compound (1) at least one of R ¹ -R ⁵ is alkyl, while the others are H. Said alkyl It can be partially or totally halogenated.

In one embodiment, R ₁ and R ₂ , as far as present, are independently selected from C1-C10 alkyls. Said C1-C10 alkyls can be partially or totally halogenated.

In a preferred embodiment, R ¹ -R ¹⁰ , as far as present, are all H, or at least one is alkyl and all others are H, and R, and R ₂ , as far as present, are independently selected from C1-C10 alkyls. Some or more of one among said alkyls may be partially or totally halogenated. R ₂ in the formula (2) can be selected as H. In particular, in the pyridinium compound (1), at least one of R ¹ -R ⁵ is selected from H and a hydrocarbon other than H, preferably an alkyl (partially or totally halogenated), the others being H. In one embodiment, A * is selected from the group of pyridinium, imidazolium and / or pyrrolidinium compounds. Preferably, A * is selected from the group of pyridinium and / or imidazolium compounds.

In one embodiment, said pyridinium, imidazolium and / or pyrrolidinium, a compound is a pyridine, imidazole and pyrrolidine ring, respectively, which is substituted on nitrogen, and which may comprise other substituents. In the case of imidazolium, one or preferably both of the ring nitrogen atoms may be substituted.

In a preferred embodiment, A ⁺ is selected in a selected manner, the compounds of formulas (I) and (II), respectively,

where:

R <and R ₂ , to the extent herein, are independently selected from the substituted or unsubstituted alkyl, alkenyl. alkynyl or aryl, which, independently, may be totally or partially halogenated;

R ^' to R ⁵ , to the extent herein, are independently selected from H and from the substituted or unsubstituted alkyl, alkenyl, alkynyl or aryl, which. independently, they can be totally or partially halogenated.

In a preferred embodiment, in the formulas (l) - (ll), R ¹ to R ^s , as far as they are present, are H. In the structure of the formula (I), at least one of R ¹ to R ^s is selected from H and alkyl, preferably at least one of R ¹ to R ⁵ is an alkyl. Preferably R ⁴ in formula (I) is an alkyl. Said alkyl may be totally or partially halogenated.

In a preferred embodiment, in the formulas (l) - (ll), R ₁ and (¾>. To the extent present, they are independently selected from a substituted or unsubstituted alkyl, alkenyl, and alkynyl. Said alkyl, alkenyl and alkynyl may be independently, totally or partially halogenated, preferably R ^, to R5, to the extent present, are H or an alkyl, said alkyl may be wholly or partially halogenated.

Preferably, R ¹ to R ⁵ , R, and R ₂ , to the extent present, is independently selected from a C1-C15 alkyl, a C2-C15 alkenyl, a C2-C15 alkynyl and a C6-C15 ring, wherein the alkyl, alkenyl, alkynyl and / or aryl can be partially or totally halogenated, and from R ¹ to R ⁸ , it can also be selected from an H. Preferably, said alkyl, alkenyl, alkynyl or aryl is selected from C1- alkyl C10, C2-C10 alkenyl, C2-C1 alkynyl and C6-C12 aryl. More preferably, R ₁ and R ₂ are selected from C1-C10 alkyls. R ⁴ in formula (I) is selected from a C1-C10 alkyl and from H, and R ¹ to R ³ and R ⁵ are H. In a preferred embodiment, A ⁺ is selected from the compounds of formulas (5) a (7), respectively,

where:

R ₁ and R ₂ , to the extent hereinbefore, are independently selected from the substituted or unsubstituted alkyl, alkenyl, alkynyl or aryl, wherein said alkyl, alkenyl, alkynyl or aryl may be, independently, partially or totally halogenated, and R ⁴ is selected from an alkyl and an H, wherein said alkyl may be partially or completely halogenated. Preferably, said alkyl, alkenyl, alkynyl or aryl is selected from C1-C15 alkyl, C2-C15 alkenyl, C2-C15 alkynyl and C6-C15 aryl. Preferably, said alkyl, alkenyl, alkynyl or aryl is selected from C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl and from C6-C12 aryl. Most preferably, R ₁ and R ₂ and is selected from a C1-C10 alkyl and R ⁴ is selected from C1-C10 alkyl and H.

In a preferred embodiment, any of said pyridinium, imidazolium and / or pyrrolidinium compounds, for example, of structures (1) - (7) or (l) - (ll), R ₁ and R ₂ , as far as present, they are independently selected from a C1-C10 alkyl, wherein one or both of said C1-C10 alkyl can be, independently, partially or totally halogenated. In these embodiments, R ¹ to R ^10, the extent present, are preferably H or alkyl. If any one or more of R ¹ to R ¹⁰ is an alkyl, any or more of said alkyls may be totally or partially halogenated.

In one embodiment, said A ⁺ cation is a di-alkyl imidazolium, in which one or both of said alkyl groups can be, independently, totally or partially halogenated. In one embodiment, said A ⁺ cation is a methyl alkyl imidazolium, wherein said alkyl can be totally or partially halogenated. For example, said alkyl can be a C1-C10 alkyl, which can be totally or partially halogenated, for example fluorinated. In a preferred embodiment, said A ⁺ cation is selected from a 1-butyl-3-methyl-pyridinium, 1-butyl-3-methyl-imidazolium and a 1-methyl-3- (3,3,4,4, 5,5,6,6,6- nonafluorohexyl) -1 H-¡midazol-3-¡(MFHI +), in particular of a 1-butyl-3-methylpyridin-1- io and 1-butyl-3- methyl-1H-imidazol-3-io. Preferably, the anion in this case may be TFSI (Bis (trifluoromethylsulfonyl) imide) ((CF ₃ S0 ₂ ) ₂ N ^" ) and / or iodide, for example.

The MFHI ⁺ cation mentioned above is an example of an A ⁺ cation comprising a substituent alkyl, which is partially fluorinated. In this case, the alkyl substituent is -CHrCH ₂ - (CF ₂ ) 4-CF ₃ . The applicant noted that the presence of MFHI * iodide improves the stability of the devices of the invention.

The ionic liquid may comprise any suitable anion. For the purpose of illustration, a few structures are provided, from which the anions can be selected. In one embodiment, said ionic liquid comprises an anion selected from halides, such as chloride, bromide, fluoride, iodide and (CF ₃ S0 ₂ ) ₂ N-, (CFaCOafeN ^" , BF _4. , PF _e ^" , NO ₃ , CH ₃ C0 ₂ , CF ₃ SO ₃ , (CFaSOafeC ^" , (CF ₃ C0 ₂ ) ₂ C ^' , and N (CN) ₂ ^' . Preferred anions are TFSI 15 and / or iodide. In one embodiment, the void transport composition of the invention comprises a combination of two or more different ionic liquids. The two or more ionic liquids preferably comprise A ⁺ cations having different structures. The anions can be the same or different.

In one embodiment, the composition of the invention comprises two different ionic liquids, comprising A1 ⁺ and A2 ⁺ cations, wherein A1 ⁺ and A2 ⁺ are independently selected from A ⁺ cations as defined elsewhere herein. specification.

In a preferred embodiment, one of the different ionic liquids comprises a pyridinium compound and the other comprising an imidazolium compound. Preferably, A1 ⁺ of pyridinium compounds is selected and A2 * is selected from imidazolium compounds as defined in the present specification.

In a preferred embodiment, the void transport composition comprises a compound (A1 ⁺ ) of formula (1) and a compound (A2 ⁺ ) of formula (2) as defined above. Preferably, the void transport composition comprises a compound (A1 ⁺ ) of formula (I) and a compound (A2 ⁺ ) of formula (II) as defined above. Preferably, the void transport composition comprises a compound (A1 *) of formula (5) and a compound (A2 ⁺ ) of formula (6) as defined above. In a preferred embodiment, the void transport composition comprises 1- butyl-1-methylpyridinium and 1-butyl-3-methyl-imidazolium.

For the purposes of these specifications, the total weight percentages (100% by weight%) are formed by the total of the organic cargo transport materials, one or more ionic liquids present in the composition and additional optional or additive compounds . Preferably, the void transport composition is considered free of any solvent, and any residual solvent is not included in the percentages provided in this specification. It is not excluded that the composition comprises several structurally different organic cargo transport materials. In a preferred embodiment, the Composition comprises only a structurally defined organic cargo transport material, which is preferably a small molecule or a particular characterized polymer, as discussed in this specification elsewhere. In a preferred embodiment, the void transport composition is free of other additives, except for the cargo transport material and one or more ionic liquids, which comprises less than 5% by weight or less than 10% molar of other additives, in addition to the organic cargo transport material and that of one or more ionic liquids. In a preferred embodiment, the void transport composition comprises 0.1% to 50% by weight of the ionic liquids and 50% to 99.9% by weight of the organic cargo transport material.

In a preferred embodiment, the void transport composition comprises from 0.3% to 30% by weight of ionic liquids and from 70% to 99.7% by weight of the organic cargo transport material and optionally other additives. The other optional additives are therefore included in the percentage of organic cargo transport material (60 to 99.9% by weight). Preferably, the void transport composition comprises from 0.5% to 20% by weight of ionic liquids and from 80% to 99.5% by weight of organic cargo transport material and optionally other additives.

In one embodiment, the void transport composition comprises 1.0% to 15% by weight of ionic liquids and 85% to 99.0% by weight of the organic cargo transport material and optionally other additives.

In one embodiment, the void transport composition comprises from 1.25% to 10% by weight of ionic liquids and from 90% to 98.75% by weight of the organic cargo transport material and optionally other additives.

In one embodiment, the void transport composition comprises 1.5% to 8% by weight of ionic liquids and 92% to 98.5% by weight of the organic cargo transport material and optionally other additives, preferably from 1.8% to 5% by weight of the ionic liquids and from 95% to 98.2% by weight of the organic cargo transport material and optionally other additives. In one embodiment, the void transport composition comprises 0.05% to 6.0% by weight of ionic liquids, preferably less than 5% by weight, and more preferably less than 1.0% to 5% by weight of ionic liquids

In a preferred embodiment, the void transport composition is free of other doping agents or additives. Preferably, the void transport composition is free of 4-tert-butylpyridine (t-BP) and / or lithium. Preferably, the void transport composition comprises less than 4% by weight, more preferably less than 2% by weight, even more preferably less than 1% by weight and more preferably less than 0.5% by weight of any of the group selected between lithium and t-BP. A low amount or absence of lithium ions is particularly preferred.

If the organic void transport material is a small molecule (as opposed to a polymer), the molar concentrations of the ionic liquids compared to the organic charge transport material can also be significant.

In one embodiment, the void transport composition comprises 0.5% to 50% molar of the ionic liquids and 50% to 99.5% molar of the organic cargo transport material and optionally other additives. The other optional additives are included in the percentage of the organic cargo transport material (50 to 99.9 mol%). Preferably, the void transport composition comprises from 1.0% to 40% molar of the ionic liquids and from 60 m% to 99.0% molar of the organic cargo transport material and, optionally, other additives.

In one embodiment, the void transport composition comprises 2.5% to 30% molar of the ionic liquids and 70% to 97.5% molar of the organic cargo transport material and optionally other additives.

In one embodiment, the void transport composition comprises 3% to 25% molar of ionic liquids and 75% to 97% molar of the organic cargo transport material and optionally other additives. In one embodiment, the void transport composition comprises from 4.5% to 20% molar of the ionic liquids and from 80% to 95.5% molar of the organic cargo transport material and optionally other additives, preferably 5 % to 15% molar of ionic liquids and 85% to 95% molar of the organic cargo transport material and, optionally, other additives.

As indicated above, the void transport composition is preferably substantially free of other dopants or additives. Preferably, the void transport composition comprises less than 4 molar%, more preferably less than 2.5 molar, even more preferably less than 1 molar and most preferably less than 0.5 molar of any of the group selected between lithium and t-BP. Preferably, lithium ions are absent or present in low concentrations, as indicated. The void transport composition preferably comprises an ionic liquid. According to the generally used definition of the term, "ionic liquid" is a salt that is liquid at 100 ° C. In one embodiment, the ionic liquid of the invention is liquid at 50 ° C, preferably at 40 ° C. A material It is considered liquid, if it has measurable liquid properties, in particular, if it has the property of a fluid (as opposed to a solid body) and any measurable viscosity. According to a preferred embodiment, a material is considered as liquid, if it has a viscosity of 20,000 cps (centipoise) or less, preferably 15,000 cps or less, more preferably 10,000 cps or less, most preferably 5,000 cps or less. The terms "molten" or "co-molten" also refer to "liquid" as defined herein. The term does not refer liquid to the gaseous state.

According to a preferred embodiment, the ionic liquid used in the present invention is liquid at room temperature or higher. The term "room temperature" refers to the temperature of 25 ° C.

The hollow transport composition comprises a cargo transport material, preferably a hollow transport material (HTM). The cargo transport material is preferably an organic cargo transport material, such as an organic HTM. An organic cargo transport material is characterized in that the electric charges, in particular the holes and electrons, move by means of electronic movement through the material. Charges are generally not transported by diffusion of molecules, as would be the case in liquid electrolytes, for example. Accordingly, the organic charge transport composition and / or the load transport material of the present invention is preferably not an electrolyte.

In a preferred embodiment, the cargo transport material is Spiro-OMeTAD (2,2 ', 7,7-tetrakis (N, N-di-p-methoxyphenylamino) -9,9-spirobifluorene). However, the present invention is not limited to a particular HTM, and HTMs other than Spiro-OMeTAD can be doped or supplemented with one or more ionic liquids in accordance with the present invention.

WO 2007/107961 discloses an organic cargo transport material, such as tris (pmethoxyethoxyphenyl) amine (TMPA) and other compounds. A particularity of these compounds is that they can be in liquid form at least during the processing of optoelectronic devices. These compounds can be used as cargo transport materials according to the present invention. Abate et al, Energy Environ. Sci., 2015,8, 2946-2953, describe triphenylamino-bound silolothiophene as stable hollow transport materials for perovskite-based solar cells with high efficiency. These cargo transport materials can also be used for the purpose of the present invention. FJ Ramos et al, RSC Adv., 2015.5, 53426-53432, and R. et al Kasparas, Triazatruxene-based Hole Transporting Materials for Highly Efficient Perovskite Solar Cells, Journal of the American Chemical Society, 2015, 137 (51), 16172-16178 discloses 5,10,15-trihexyl-3,8,13-trimethoxy, 15-dihydro-5H-dindole [3,2-a: 3 ', 2'-c] carbazole (HMDI) or 5,10,15-tris (4- (hexyloxy) phenyl) -10,15-dihydro-5H-diindolo [3,2-a: 3 ', 2'-c] carbazole (HPDI) and other transport materials loading with triazatruxen as core-base.

In one embodiment, the organic cargo transport material is selected from spirofluorenes, such as spiro-OMeTAD (2,2 ', 7,7'-tetrakis (N, N-di-p-methoxyphenyl amine) -9.9- spirobifluorene) and derivatives of this and other spirofluorenes, carbazol and its derivatives, triazatruxene and derivatives thereof, compounds comprising the thiophene nucleus and derivatives thereof, triphenylamine and its derivatives, acene and derivatives thereof, and 2, 7'-bis (4-methoxyphenyl) amino) spiro [cyclopenta [2,1-b: 3,4- b '] dithiophene-4,9'-fluorene and derivatives thereof. In one embodiment, the organic cargo transport material is 2 ', 7-bis (4- methoxyjphenyl) amino) spiro [cyclopenta [2,1-b: 3,4-b'] dithiophene-4,9'- Fluorene (FDT). This compound showed interesting properties as organic cargo transport materials, in particular, when combined with the ionic liquid additive according to the invention.

In a preferred embodiment, the organic cargo transport material is not a polymeric compound and / or a small molecule. For the purpose of this specification, a small molecule is a compound that has a molecular weight (or molecular mass) of ≤ 5,000, preferably ≤ 4,000, more preferably ≤ 3,000 and most preferably ≤ 2,000 (dalton).

In an alternative embodiment, the organic cargo transport material may be a polymeric compound. Examples of organic cargo transport materials are poly-3,4ethylenedioxythiophen (PEDOT), in particular PEDOT: PSS, polytriarylamines, such as (PTAA) and its derivatives containing fluorene and indenofluorene, called PF8-TAA, and PIF8-TAA, polyfluorene derivatives (PFO, TFB and PFB), polyaniline (PAÑI), poly (p-phenylene 20) (PPP), polythiophene (PT) and its derivatives, such as thiophene poly3-hexyl (P3HT) and poly (4.4 ' bis (N-carbazolyl) -1,1-biphenyl) (PPN).

In one embodiment, the organic cargo transport material comprises one or more selected from the group of: PTAA (poly [bis (4-phenyl) (2,4,6-trimethylphenyl) amine]),

diyl}]), and derivatives of one or more of the aforementioned.

The non-polymeric cargo transport materials and polymers mentioned above are examples of organic materials that can be doped by the addition of an ionic liquid according to the present invention.

The present invention encompasses optoelectronic and / or electrochemical devices comprising a layer of void transport material comprising the composition of the void transport material of the invention. Examples are solar cell devices, such as sensitized solar cells, for example dye solar cells or perovskite-based solar cells. In one embodiment, the solar cell is based on an organic-inorganic perovskite or a perovskite oxide. Preferably, the sensitized solar cells are solid state devices and / or lack an electrolyte, in particular, a liquid electrolyte comprising a redox pair. In one embodiment, the solar cell is a solid-state hybrid solar cell.

Figures 7 and 8 schematically illustrate the solar cells 1 prepared according to the invention. The solar cells of the invention are generally flat and / or layered devices, comprising two opposite sides 7 and 8. The device of Figure 7 comprises a conductive current collector layer 5, a semiconductor layer of type n 2, a light collector or sensitized layer 3, a gap transport layer 4 and a layer to provide a current of embodiment 6, wherein the gap transport layer 4 is between said light harvester layer 3 and a layer for providing stream 6, said a gap conveyor layer comprising a cargo transport composition of the invention. In another embodiment, the invention provides a solar cell 1, as illustrated in Figure 8, comprising a surface augmentation structure 9. The remaining reference numbers are as disclosed with respect to Figure 7. The structure Surface augmentation 9 can be a nanoporous, mesoscopic structure, which can be made from nanoparticles, for example. The surface augmentation structure 9 may be an insulating oxide, for example, alumina (Al ₂ 0 ₃ ), zirconia, silicon oxide (Si0 ₂ ), etc., or a n-type semiconductor material and / or may comprise the same material than layer 2. Titanium dioxide (Ti0 ₂ ) or other metal oxide semiconductor materials can be used for layers 2 and / or 9, for example. The light collecting layer 3 is preferably provided between the surface augmentation structure 9 and the gap transport layer 4 comprising the composition of the invention.

Examples 1-4 and Comparative Examples 5-6

Material and methods

Chemical products were purchased from Sigma Aldrich or Agros and were used without any treatment or purification. Spiro-OMeTAD represented as 2,2 ', 7,7'-tetrakis (N, N-di-p methoxyphenylamine) -9,9-Spirobifluorene (Spiro-MeOTAD) was purchased from Merck KGaA, while methylamine iodide, CH ₃ NH ₃ I (IMA), was synthesized according to known literature.

Device manufacturing:

The perovskite (CSP) solar cell devices were manufactured in FTO coated glass (TEC, Pilkington) modeled by laser engraving. Before any deposition, the substrates were cleaned using a Hellmanex® solution and subsequently rinsed with deionized water and ethanol. After this, they were sonicated in acetone, rinsed with ethanol and 2-propanol and dried through compressed air. A compact layer of T0 ₂ was deposited by spray pyrolysis at 450 ° C using 1 ml of titanium bis diisopropoxide (acetyl acetonate) as a precursor solution (75% in 2-propanol, Sigma Aldrich) dissolved in 19 ml of ethanol pure using 0 ₂ as carrier gas. After deposition of the blocking layer (Ti0 ₂ compact layer), the substrates were maintained for an additional 30 minutes at 450 ° C for anatase phase formation. Once the samples reached room temperature, they were treated with titanium tetrachloride (TiCI) (immersion in a 0.02M solution of TiC in deionized water at 70 ° C for 30 minutes) in order to obtain a homogeneous layer. Then, The samples were washed with deionized water, heated at 500 ° C for 10 minutes and cooled to room temperature. After this, a mesoporous layer of Ti0 ₂ (DYESOL, 30NRD) was deposited by centrifugation coating (4000 rpm for 30 s with 2000 rpm seconds ^{' 1} as acceleration) and the samples were annealed by heating them progressively at 450 ° C for 2 hours. On top of this, a mixed perovskite of organic cation and halide ((FAPbl ₃ ) or, 85 (MAPbBr ₃ ) or 15) was deposited by a one-step method. A mixture of 1.4 M of lead iodide (Pbl ₂ ), lead bromide (PbBr ₂ ) and a mixture of formamidinium iodide (FAI) and methyl ammonium bromide (MABR) were mixed in a solvent mixture of N, N-dimethylformamide (DMF) and dimethylsulfoxide (DMSO). The solution was prepared inside an argon glove box under controlled conditions of humidity and oxygen (H ₂ 0 level: <1 ppm and 0 _{2 level} : <10 ppm) and kept under stirring at 80 ° C during the night in order to completely dissolve Pbl ₂ . Deposition of perovskite was carried out by a one-step method with solvent engineering. In this method, the perovskite precursor solution was deposited by centrifugation over the mesoporous layer at 1,000 rpm for 10 seconds and then 6,000 rpm for 30 seconds. During the second step, chlorobenzene dripped into the center of the substrate in the last 15 seconds. After the solvent treatment, the samples were transferred to a hot plate and annealed at 100 ⁰ C for 60 minutes. HTM Preparation:

For the hole transport material, 72.3 mg of Spiro-MeOTAD was dissolved in 1 ml of chlorobenzene. 1-Butyl-1-methylpyridin-1-io (trifluoromethylsulfonyl) imide (BMP TFSI) ionic liquid was used as a dopant / additive for Spiro-MeOTAD.

The stock solution of ionic liquid was prepared by adding 35 mg of 1-butyl-1- methylpyridin-1-io bis (trifluoromethylsulfonyl) imide (BMP-TFSI) in 1 ml of acetonitrile. Then, the solutions of the void transport layer were prepared by adding different amounts of this stock solution in the 72.3 mg / mi Spiro-MeOTAD solution to obtain 0 mM, 3.2 mM, 4.7 mM, 6.1 mM and 7.5 mM concentration of BMP-TFSI respectively. For comparison, the standard doped Spiro-MeOTAD solution was prepared by dissolving 72.3 mg of Spiro-MeOTAD in 1 ml of chlorobenzene, and adding as standard additives 17.5 μΙ of a lithium bis-imide (trifluoromethylsulfonyl) (LiTFSI) stock solution (520 mg of LiTFSI in 1 ml of acetonitrile), 21.9 μΙ of an FK209 (Tris (2- (1H-pyrazol-1-yl) -4-tert-butll) ridinna) -cobalt (lll) Tris (bis (trifluoromethylsulfonyl) imide))) stock solution (400 mg in 1 ml acetonitrile) and 28.8 μΙ of 4-tert-butylpyridine (t-BP).

Next, 35 μΙ of each HTM solution was thrown onto the perovskite substrates of the solar cell samples described above, and the samples were coated by centrifugation at 4,000 rpm for 30 seconds. Then, 80 nm of gold was used as a cathode which was thermally evaporated on the HTM under a vacuum between ^1-10-6 and ^1-10-5 torr, such as to obtain exemplary solar cells.

Characterization:

Current-voltage density curves were recorded with a Keithley 2,400 measuring device under AM 1, 5 G, 100 mW-cm ² with illumination of a certified AAA Class, 450 W solar simulator (Oriel 94023 A). The light power was calibrated using a monocrystalline silicon cell certified by solar cells. A black metal mask (0.16 cm ² ) was used as an active area of the square solar cells (0.5 cm ² ) during the measurement to reduce the influence of scattered light.

The IPCE measurements were made using a 150W Newport Xenon lamp coupled to a motorized Oriel Cornerstone 260 ¼ m mono-Chromator as a light source, and a 2936-R Energy Meter to measure the short-circuit current.

Results and Discussion:

The photovoltaic performance of the devices prepared is shown in Figures 1 and 2 and in Table 1 below.

Table 1: Photovoltaic properties of device-s prepared using different concentrations of BMP TFSI ionic liquid and the comparison with Spiro-OMeTAD using FK209 as a dopant, LiTFSI salt and t-BP additives.

All HTM with BMP TFSI showed at least good or better performance than HTM 6 containing only Spiro-OMeTAD. The cell of Example 2 showed the best performance of all devices, and, in particular, a higher yield than the cell of Example 3 and 4, which had a higher concentration of BMP. In the case of the (comparative) solar cell Example 6 containing only Spiro-OMeTAD, the open circuit voltage (Voc) and the short-circuit current density (Jsc) were around 0.57 V and 18.38 mA .cm ^'2 , respectively. While in the case of the solar cell of Example 2, the Voc and Jsc values have been greatly improved to 1.02 V and 21.17 mA.cm ^'2 , respectively. The filling factor (FF), which reveals the intrinsic resistance and the degree of load recombination, also increased from 32.5% to 65.1%. Apparently, the devices of Example 2 exhibit the optimal BMP TFSI ionic liquid concentration for Spiro-OMeTAD HTM and showed the best performance when achieving an energy conversion efficiency (PCE) of 14.06%. This PCE value is very close to that of conventional solar cells based on spiro-OMeTAD HTM containing FK209 as a dopant, and the additives LiTFSI and t-BP (PCE = 14.96%, Comparative Example 5).

These results show that ionic liquids are promising candidates for doping organic cargo transport materials.

Figure 2 further reveals that in all examples 1-4, a broad plateau was observed over the entire visible spectral range and up to 85% of the photons can be successfully converted to electricity in the case of the optimized concentration used. in Examples 1-4. The highest IPCE was observed in the cell of Example 2. These results were in accordance with the J-V measurements.

Table 2 shows the amounts in percent by weight and the mole percent of HTM and ionic liquid in the void transport compositions of Examples 1-4. Table 2: Molar and weight percentages of HTM and Ll (Ionic Liquid) compositions of the hollow conveyor material of the invention.

The values of power conversion efficiencies (PCE) in Table 2 were taken from Table 1. The highest values were for the devices of Examples 1-4, but began to decrease slightly in Example 3. Consequently, Especially good results were achieved when the compositions of the void transport material (100% = HTM + Ll) contained approximately 5.3% to 12.3% molar ionic liquid (87.7-94.7 mol% HTM organic) and 1.9% to 4.6% by weight of ionic liquid (98.1% to 95.4% by weight of HTM organic material), respectively.

Examples 7-12: BMIM ionic liquid combinations

Solar cells were prepared as described above for Examples 1-6, using 1-butyl-3-methyl-1H-imidazol-3-io bis ((trifluoromethyl) sulfonyl) imide (BMIM TFSI) (Example 7) and combinations of BMIM TFSI with 1-butyl-3-methylpyridin-1-iobis ((trifluoromethyl) sulfonyl) imide (BMP TFSI).

In Examples 7-12, the amount and molar concentrations of the ionic liquid (Example 7) or the combination of ionic liquids (Examples 8-12) was kept constant at the values corresponding to Example 2 above (4.7 mM) . It is observed that the molecular weight of BMIM TFSI and BMP TFSI are very similar, so that the ratios indicated in Table 3 reflect weight relationships, as well as molar ratios of the two cations (PM (BMP TFSI) = 430.05 ; PM (BMIM TFSI) = 419.36). Table 3: Energy conversion efficiency in solar cells based on BMIM TFSI ionic liquid and combinations of ionic liquids.

In Examples 7-12, solar cells containing void transport compositions containing combinations of different ionic liquids in organic void transport materials did not reach as high power conversion efficiencies as cells containing a single ionic liquid such as dopant / additive. On the other hand, the combinations provide additional advantages over the stability of solar cells.

Claims

1. A void transport composition comprising an organic cargo transport material and an ionic liquid comprising an A ⁺ cation, wherein A ⁺ is a 5 or 6 membered substituted or unsubstituted heterocyclic ring having 1- 3 heteroatoms, which are independently selected from N, S and O, with the proviso that at least one of the heteroatoms is a quaternary nitrogen atom.

2. The void transport composition of claim 1, wherein said 5 or 6 member ring comprises a substituted nitrogen atom and optionally the carbon atom substituents.

3. The void transport composition of any of the preceding claims, wherein said 5 or 6 member ring comprises a carbon atom substituents.

4. The void transport composition of claim 1, wherein A ⁺ is selected from the group of the pyridinium, imidazolium and / or pyrrolidinium compounds.

5. The void transport composition of claim 4, wherein said pyridinium, imidazolium and / or pyrrolidinium compound is a pyridine, imidazole and pyrrolidine ring, respectively, which is substituted on nitrogen, and which may comprise other substituents

6. The void transport composition of any of the preceding claims, wherein A * is selected from the compounds of formulas (1) to (4),

where: R ₁ and R ₂ , to the extent hereinbefore, are independently selected from substituted or unsubstituted alkyl, alkenyl, alkynyl or aryl, wherein said alkyl, alkenyl, alkynyl or aryl may, independently, be partially or totally halogenated; R ¹ to R ¹⁰ , to the extent herein, is independently selected from H and substituted or unsubstituted alkyl, alkenyl, alkynyl or aryl, wherein said alkyl, alkenyl, alkynyl or aryl may be, independently, partially or fully halogenated

7. The void transport composition of any of the preceding claims, wherein A * is selected from the compounds of formulas (5) a

(7),

where:

R ₁ and R ₂ , to the extent herein, are independently selected from the substituted or unsubstituted alkyl, alkenyl, alkynyl or aryl, wherein said alkyl, alkenyl, alkynyl or aryl may be, independently, partially or fully halogenated, and R ⁴ , as far as it is present, is selected from alkyl and from H, wherein said alkyl may be partially or totally halogenated.

8. The void transport composition of any of claims 6 and 7, wherein, in said pyridinium, imidazolium and / or pyrrolidinium compounds, R ₁ and R ₂ , to the extent herein, are independently selected from C1-C10 alkyl, R ⁴ is selected from H and from C1-C10 alkyl, wherein any one or both of said C1-C10 alkyl can be, independently, partially or totally halogenated.

9. The void transport composition of any of the preceding claims, wherein A * is selected from 1-butyl-l-methylpyridinium, 1-butyl-3-methylimidazolium, and 1-methyl-3- (3 , 3,4,4,5,5,6,6, & - nonafluorohexyl) -1 H-imidazol-3-io.

10. The void transport composition of any of the preceding claims, wherein said ionic liquid comprises an anion selected from halides, such as chloride, bromide, fluoride, iodide and from (CFsSO ^ N ^' , (CFaCO ^ N ^' , BF _4. , PF _e ^" , NO3-, CH3CO2, CF3SO3, (CF ₃ S02) 2C -, (CF ₃ C02) 2C-, and N (CN) ₂ \

11. The void transport composition of any of the preceding claims, comprising from 0.1% to 50% by weight of the ionic liquids and from 50% to 99.9% by weight of the organic cargo transport material .

12. The void transport composition of any of the preceding claims, wherein said organic cargo transport material is selected from spirofluorenes, such as spiro-OMeTAD (2,2 ', TJ-tetrakis (N, N-di -p-methoxyphenyl amine) -9,9-spirobifluorene), derivatives of this and other spirofluorenes, carbazol and its derivatives, triaza-truxene and its derivatives, compounds comprising the thiophene core and its derivatives, triphenylamine and derivatives thereof , acene and its derivatives, 2 ', Tb \ s (4-methoxyphenyl) amino) spiro [cyclopenta [2,1-b: 3,4-b'] dithiophene-4,9-fluorene and derivatives thereof.

13. An optoelectronic and / or electrochemical device, comprising the void transport composition of any of claims 1-12.

14. The optoelectronic and / or electrochemical device of claim 13, comprising a void transport layer, the void transport layer comprising the void transport composition of any of claims 1-13.

15. The optoelectronic and / or electrochemical device of claim 13 or 14, which is a solar dye cell or sensitized light collector.

16. The optoelectronic and / or electrochemical device of any of claims 13 to 15, which is a solar cell based on organic-inorganic perovskite or perovskite oxides.

17. The use of the void transport composition of any of claims 1 to 12 as a dopant and / or additive to a perovskite solar cell.