Photovoltaic devices containing cyclobutane-based hole transport materials

Abstract

To provide a hole transporting material that can be used in a high efficiency solar cell, that can be prepared using a minimal number of industrially scalable steps, that is readily available or low-cost materials, and that keeps the material costs and impact on the environment very low.SOLUTION: The teachings of the present disclosure pertain to hole transporting compounds containing a cyclobutyl moiety, which can be made into organic hole conductors and into hole transporting material. Additionally, optoelectronic and photoelectrochemical devices comprising such hole transporting material or hole transporting compound, in particular photovoltaic devices, organic-inorganic perovskite films, layered photovoltaic devices, p-n heterojunctions, dye-sensitized solar cells, organic solar cells and solid-state solar cells, are described. Notably, a perovskite solar cell module fabricated using a disclosed HTM compound exhibits a record efficiency over 19.0% with an active area of 30.24 cm2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to hole transport compounds containing a central cyclobutyl moiety, organic hole conductors, and hole transport materials comprising such compounds, and optoelectronic or photoelectrochemical devices comprising such hole transport materials or hole transport compounds, particularly photovoltaic devices, pn heterojunctions, dye-sensitized solar cells, organic solar cells, and solid-state solar cells. The present invention also relates to methods for preparing such organic hole conductors, layers, and photoelectrochemical devices. Background and problems underlying the invention

[0002] In the last decade, there has been intense interest in renewable energy sources, especially the most promising one: the sun. The conversion of solar energy into electric current using thin-film, third-generation photovoltaics (PV) has been widely investigated in the last two decades. Sandwich / monolithic PV devices consisting of an organic / inorganic light harvester, a redox electrolyte / solid-state hole conductor, and a mesoporous photoanode with a counter electrode have gained considerable interest due to their ease of fabrication, flexibility in material selection, and low cost of production.

[0003] In recent years, organic-inorganic hybrid perovskite solar cells (PSCs) have attracted considerable global attention due to their low cost and easy fabrication. [1] Since 2009, when Miyasaka and co-authors reported a power conversion efficiency (PCE) of 3.8% for PSCs. [2] However, the performance of these photovoltaic devices has increased dramatically, with PCEs now exceeding 25%.

[0004] Hole transport materials are one of the typical components required for efficient PV devices. These materials are responsible for transporting photogenerated carriers from the absorber towards the electrode. Hole transport materials should exhibit sufficient charge transport properties, suitable energy levels, especially their highest occupied molecular orbital (HOMO) level, and good thermal stability. [3]These materials are the weak link in the overall PV device. Despite significant research efforts being devoted to the development of new hole transport materials, the field is still dominated by 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiroOMeTAD) as an organic hole transport material (HTM). Unfortunately, the synthesis procedure for this HTM is a long and complicated procedure requiring the use of expensive lead catalysts, sensitive (n-butyllithium) Grignard reagents, aggressive (Br2) reagents, and low temperatures (-78 °C). [4] Furthermore, to ensure maximum performance, Spiro-OMeTAD must be purified by sublimation, which necessarily drives up the cost of the material.

[0005] Because the synthesis of spiro-OMeTAD is extremely expensive, the development of low-cost and efficient HTMs remains a crucial challenge for large-scale applications.1 Synthetic efforts undertaken to replace spiro-OMeTAD have yielded several classes of HTM molecules that exhibit good charge transport and comparable performance in PV devices; however, the vast majority of these derivatives still require expensive catalysts and multi-step synthetic procedures.

[0006] Previously discovered synthesis processes for hole transport materials involve commercially unavailable and expensive starting compounds, very low reaction temperatures, aggressive reagents, and complex reaction steps (e.g., five steps for the synthesis of spiro-OMeTAD). Therefore, the synthesis processes are lengthy, time-consuming, and expensive, and have significant environmental impacts. The present invention provides hole transport materials that can be used in high-efficiency solar cells, can be prepared using a minimum number of industrially scalable steps, and are readily available or low-cost materials, keeping material costs and environmental impacts very low.

[0007] Carbazole has been recognized as a promising core unit for molecular design because it can be substituted with a wide range of desired groups, allowing for fine tuning of optical and electrochemical properties. [5] Various attachments, including carbazole as the electron-donating unit at the outer edge, are routinely used to tune the HOMO level and are added to PSCs, demonstrating comparable photovoltaic performance. [6-8] This is the star-shaped SGT series [9,10] , benzodithiazole

[11] , bismethylenebenzene [12,13] , bipyridine

[14] , pyrene-based

[15] Photodimerized carbazoles are attractive building blocks due to their simple, elegant, and environmentally friendly synthesis, and have been explored in early studies as excimer-free and high hole carrier mobility materials. [16-18] .

[0008] Herein, we disclose the development of novel HTMs, which contain cyclobutane as a novel structural core element, with side chains composed of two differentially substituted, branched, photodimerizable carbazole arms. The specific placement of the carbazolyl groups on the cyclobutane core may also facilitate carrier transport processes. Furthermore, the bulky and sterically hindered rigid trans configuration results in a conflict between planarization and repulsive conformational hindrance, leading to pseudospiro-type configurations and diversified torsion angles. The effects of different peripheral carbazole substituents on various properties of the newly synthesized molecules have been systematically investigated. The novel cyclobutane-based HTMs have been successfully incorporated into PSCs and have shown PCEs of up to 21% and improved long-term stability under ambient conditions compared to spiro-OMeTAD. Most importantly, to obtain novel HTMs, we have an applicable protocol inspired by green science and show, for the first time, that HTMs for PSCs may be synthesized without sacrificing efficiency and eliminating the use of hazardous materials, thus reducing adverse environmental impacts. Summary of the Invention

[0009] The object of the present invention is to provide new hole-transporting organic compounds with suitable energy levels that do not require a sublimation step for post-synthesis purification, as is the case with the synthesis of spiroOMeTAD.

[0010] The present teachings also provide new hole-transporting materials that provide higher power conversion efficiencies (PCEs) in photovoltaic devices that include perovskite, organic, or organometallic dyes as sensitizers. [Brief explanation of the drawings]

[0011] [Figure 1] Microscope images of the cross-sections of photovoltaic cells are shown, including samples FTO / SnO2 / perovskite / spiroOMeTAD / Au (left) and FTO / SnO2 / perovskite / cyclobutyl-HTM / Au (right). [Figure 2] 1 shows the current-voltage curves of a photovoltaic cell in which compounds 1, 5 and 7, corresponding to compounds V1244, V1366 and V1321, and spiro-OMeTAD are investigated as hole transport materials. [Figure 3] Figure 1 shows the photovoltaic current-voltage curves in which compounds 2, 3, 4 and 6 corresponding to V1296, V1297, V1361, V1367 are investigated as hole transport materials. DETAILED DESCRIPTION OF THE INVENTION

[0012] The main object of these teachings is new compounds of formula (I) containing a cyclobutane moiety. [ka]

[0013] R,R 1is a monocyclic or polycyclic ring system containing at least one pair of conjugated double bonds (-C=CC=C-), where polycyclic ring systems include fused aromatic rings or monocyclic aromatic rings bonded together by covalent bonds, or heteroaromatic systems having N, O, S, Se, Si heteroatoms. The monocyclic or polycyclic ring systems are substituted with H, halogen, cyano, C1-C20 cyanoalkyl, C1-C20 alkyl, C1-C20 alkoxy, C1-C20 alkoxyalkyl, C1-C20 haloalkyl, or C1-C20 haloalkoxyalkyl, and the cyanoalkyl, alkyl, alkoxy, alkoxyalkyl, haloalkyl, haloalkoxyalkyl, C4-C20 aryl, C4-C20 alkylaryl, C4-C20 alkoxyaryl, C4-C20 alkenylalkylaryl, C4-C20 alkoxyarylalkenyl, and C4-C20 bisalkoxyarylalkenyl groups, when they contain 3 or more carbons, may be linear, branched, or cyclic, and wherein halogen is selected from Cl, F, Br, or I.

[0014] According to another embodiment, the hole transporting compound of formula (I) containing a cyclobutyl moiety is selected from, but not limited to, a compound according to any one of formulas (1) to (52): [ka] [ka] [ka] [ka] [ka] [ka] [ka]

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[0015] In yet another embodiment, the present invention provides a hole transport material comprising at least one molecule having hole transport properties and a combination of two or more of the above selected from compounds of general formula (I). The compounds of general formula (I) are for use as organic non-polymeric semiconductors. More specifically, the present invention provides a hole transport material selected from at least one compound of general formula (I).

[0016] The present invention also provides, in another embodiment, an optoelectronic and / or photoelectrochemical device comprising a compound of formula (I). The optoelectronic and / or photoelectrochemical device comprises a hole transport material, said hole transport material comprising a compound of formula (I).

[0017] The optoelectronic and / or photoelectrochemical device is selected from an organic photovoltaic device, a photovoltaic solid state device, a pn heterojunction, an organic solar cell, a dye-sensitized solar cell, or a solid state solar cell.

[0018] In a preferred embodiment, the optoelectronic and / or photoelectrochemical device, in particular a photovoltaic solid-state device, comprises a conductive support layer, a surface-enhanced deposit structure or electron transport layer, a photosensitizer or photosensitive layer, a hole transport layer comprising a cyclobutyl-based compound of formula (I), a counter electrode, and / or a metal layer. Further, the optoelectronic and / or photoelectrochemical device is a photovoltaic solid-state device that is a solid-state solar cell comprising an organic-inorganic perovskite as a photosensitizer.

[0019] According to another embodiment, the optoelectronic and / or photoelectrochemical device is a solar cell selected from an organic solar cell, a dye-sensitized solar cell, or a solid-state device.

[0020] In yet another embodiment, the hole transport layer of an optoelectronic and / or photoelectrochemical device, particularly a photovoltaic solid-state device, is made of a hole transport material comprising at least one small molecule hole transport material selected from compounds of formula (I):

[0021] The conductive support layer is preferably substantially transparent. By "transparent" is meant transparent to at least a portion, preferably a large portion, of visible light. Preferably, the conductive support layer is substantially transparent to all wavelengths or forms of visible light. Additionally, the conductive support layer may be transparent to non-visible light, such as, for example, ultraviolet and infrared radiation.

[0022] The conductive support layer preferably functions as and / or includes a current collector for collecting current obtained from the photovoltaic solid-state device. The conductive support layer comprises a material selected from indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), ZnO-Ga2O3, ZnO-Al2O3, tin oxide, antimony-doped tin oxide (ATO), SrGeO3, and zinc oxide, and is preferably coated on a transparent substrate such as plastic or glass. In this case, the plastic or glass provides the support structure for the layer, and the aforementioned conductive material provides electrical conductivity. Such support layers are commonly known as conductive glass and conductive plastic, respectively, and are preferred conductive support layers according to the present invention.

[0023] According to another embodiment, the surface area-increasing deposit structure is nanostructured and / or nanoporous. The deposit structure is therefore preferably nanoscale. The structure of the deposit structure increases the effective surface area compared to the surface area of ​​the conductive support. The deposit structure is made of and / or contains a metal oxide as an electron transport material. For example, the material of the deposit structure is selected from semiconductor materials such as Si, TiO2, SnO2, Fe2O3, ZnO, WO3, Nb2O5, CDS, ZnS, PbS, Bi2S3, CdSe, CdTe, SrTiO3, GaP, InP, GaAs, CuInS2, CuInSe2, or combinations thereof.

[0024] According to one embodiment, the photosensitive layer of the photovoltaic solid-state device comprises at least one dye selected from organic, inorganic, organometallic, organic-inorganic dyes, or combinations thereof. The photosensitizer is preferably a compound or material that absorbs light. Preferably, the photosensitizer is a dye, and most preferably, the photosensitizer is an organic-inorganic dye. The photosensitive layer may comprise one or more dyes from the group consisting of organometallic sensitizer compounds, metal-free organic sensitizer compounds, inorganic sensitizer compounds, such as quantum dots, aggregates of organic dyes, nanocomposites, especially organic-inorganic perovskites, and combinations of the above. For the purposes of the present invention, in principle, any type of dye or photosensitizer can be used, including combinations of different types of dyes or different dyes of the same type.

[0025] According to a preferred embodiment, the photosensitive layer of a photovoltaic solid-state device is coated with a layer comprising a compound of formula (I). Preferably, said photosensitive layer comprises an organic-inorganic perovskite.

[0026] According to a preferred embodiment, the photosensitizer or photosensitive layer comprises, consists of or is made from an organic-inorganic perovskite, provided as a film of one perovskite dye, or a mixture of perovskite dyes, or a perovskite dye mixed with a further dye or photosensitizer.

[0027] According to a further embodiment, the photosensitive layer comprises another dye in addition to the organic-inorganic perovskite dye, said another dye being selected from an organic dye, an organometallic dye, or an inorganic dye.

[0028] According to another embodiment, the optoelectronic and / or photoelectrochemical device is a dye-sensitized solar cell (DSC) comprising a compound of formula (I) as a hole transport material and a dye selected from an organic dye, an organometallic dye, an inorganic dye, or a combination thereof as a photosensitizer.

[0029] The term "perovskite" for purposes of this specification refers to a "perovskite structure" and not to the specific perovskite material, CaTiO. For purposes of this specification, "perovskite" encompasses, and preferably relates to, any material having the same type of crystal structure as calcium titanate, and in which a divalent cation is replaced by two distinct monovalent cations. Perovskite structures have the general stoichiometry AMX, where "A" and "M" are cations and "X" is an anion. The "A" and "M" cations can have various valencies; for example, in the native perovskite mineral (CaTiO), the A cation is divalent and the M cation is tetravalent.

[0030] In a further embodiment, the organic-inorganic perovskite layer material comprises a perovskite structure of formula (II):

[0031] AMX3(II) where A is an alkali metal ion, preferably Li + , Na + , K. + , Rb + , Cs +, ammonium, or amidinium ions, in which one or more hydrogen atoms are replaced by alkyl or acyl groups. The ammonium ions include mono-, di-, tri-, and tetra-alkylammonium ions, in which one or more hydrogen atoms are replaced by alkyl groups. Preferably, the substituents are alkyl groups or groups independently selected from C1-C6, preferably methyl or ethyl groups. The ammonium ions, N-alkylamidinium ions, and imidinium ions, in which one or more hydrogen atoms are replaced by alkyl groups. Preferably, the amidinium or imidinium ions are selected from C1-C6 carboxyamide groups, preferably formamidium or acetamidium groups. The hydrogen atoms in the organic cation A may be replaced by halogens selected from F, Cl, I, and Br, preferably F or Cl. Preferably, A is Cs + or methylammonium ion (MA + ) or formamidium ion (FA + ) M is Cu 2+ , Ni 2+ , Co 2+ , Fe 2+ , Mn 2+ , Cr 2+ , Pd 2+ , Cd 2+ , Ge 2+ , Sn 2+ , Pb 2+ ,EU 2+ , and Yb 2+ From the group consisting of, preferably Pb 2+ , Sn 2+ is a divalent metal cation selected from X is Cl - , Br - , I - , N.C.S. - , C.N. - , and N.C.O. - From the group consisting of, preferably Cl - , Br - , or I - are monovalent anions independently selected from the group consisting of: X may be the same or different;

[0032] According to a preferred embodiment, examples of organic-inorganic perovskites are methylammonium lead halides, such as methylammonium lead iodide (CHNHPbI), methylammonium lead mixed halides, such as CHNHPbClI, formamidium lead halides, such as HC(NH)PbI, HC(NH)PbBr, or HC(NH)PbClI, cesium lead iodide (CsPbI), cesium tin iodide (CsSnI).

[0033] In a further embodiment, the organic-inorganic perovskite layer material comprises a mixed perovskite structure, wherein A is a mixture of two or more cations as defined above, and X is a mixture of two or more anions as defined above. Preferably, A is a mixture of two cations, M is Pb, and X is a mixture of two anions. Chemical formula (II) may be expressed as the following chemical formula (III): A 1 1-y A 2 y PbX 1 3-z X 2 z (III) where A 1 and A 2 is an organic monovalent cation as defined above for A.

[0034] X 1 and X 2 is Cl - , Br - , I - , N.C.S. - , C.N. - , and N.C.O. - and z is in the interval between 0.2 and 2. General synthesis scheme for compounds of general formula (I)

[0035] Hole-transporting compounds containing a cyclobutane moiety corresponding to general chemical formula (I) were prepared by a three-step synthetic route shown in Scheme 1. The first step was the photochemical cyclodimerization of commercially available 9H-vinylcarbazole (Sigma-Aldrich) according to reference (J. Polym. Sci. A 1987, 25, 1463), followed by the cyclodimerization of precursor A (

number

[0036] Hole-transporting compound 7 containing a cyclobutyl moiety and corresponding to general chemical formula (I) was synthesized, for example, via Suzuki cross-coupling between intermediate B and 4-methoxy-N-(4-methoxyphenyl)-N-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]aniline (TCI Europe NV) in the presence of palladium(II) acetate, tri-tert-butylphosphonium tetrafluoroborate, and sodium tert-butoxide (Scheme 2). [ka] Scheme 2 Synthetic routes to hole transport materials7. A general preparative scheme for perovskite solar cells

[0037] Etched fluorine-doped tin oxide (FTO) is used as the substrate for the device and cleaned before assembly. The cleaned FTO is then spin-coated with a solution of SnO2 and water, then dried and briefly heated to 190 °C. The remaining steps are performed under nitrogen. A perovskite precursor solution is prepared using a standard stock solution in DMSO / DMF and then spin-coated onto the substrate. The resulting perovskite film is annealed at 100 °C. A solution of hole transport material is prepared with the hole transport compound of interest, chlorobenzene, and any optional additives. An HTM layer is added to the perovskite film by spin-coating, and then a gold electrode is deposited by thermal evaporation. Figure 1 shows a cross-sectional view of the resulting photovoltaic cell using a cyclobutyl-based hole transport material of compound 5 (V1366). example

[0038] Information regarding practical example embodiments is provided below, describing the mode of preparation of compounds (1-7) of the present invention and its properties. This information is provided for illustrative purposes and is not intended to limit the scope of the present invention. Synthesis of intermediates A and B 1,2-bis(9H-carbazol-9-yl)cyclobutane (A) [ka]

[0039] A solution of 9-vinylcarbazole (12 g, 62 mmol) in acetone (125 mL) was irradiated (GR.E. 125 W Helios italquartz) at room temperature for 15 hours. Air was continuously bubbled through the solution. The precipitated product was filtered and recrystallized from acetone. The precipitated product was recovered as pale cream-colored crystals (8.5 g, 70.8% yield).

[0040] 1 H NMR(400MHz,THF-d6)δ8.02(d,J=8.0Hz,4H),7.72(d,J=8.0Hz,4H),7.34(t,J=7.6Hz ,4H),7.13(t,J=7.6Hz,4H),6.53-6.29(m,2H),3.22-2.99(m,2H),2.80-2.63(m,2H)

[0041] 13 C NMR(101MHz,THF)138.27,123.59,121.69,118.15,117.15, 107.88,52.48,18.59) 1,2-bis(3,6-dibromo-9H-carbazol-9-yl)cyclobutane (B) [ka]

[0042] Compound (A) (1.9 g, 4.9 mmol) was dissolved in THF (50 mL). 20% H2SO4 (50 mL) solution was then added. Next, KBr and KBrO3 solution (69 mL H2O, 4.1 g KBr, 1.15 g KBrO3) was slowly added dropwise at 10 mL / min and stirred at room temperature for 72 hours. The precipitate was collected by filtration, washed with water, and then washed three times with hot methanol. The precipitated product was recovered as white crystals of product B (3.1 g, 88.6% yield).

[0043] 1H NMR (400MHz, THF-d6) δ8.26(s,4H),7.65(d,J=8.8Hz,4H),7.50(d,J=8.8Hz,4H),6.41-6.13(m,2H),3.14-2.96(m,2H),2.85-2.64(m,2H) 13 C NMR(101MHz,THF)δ139.05,129.02,124.33,123.45,112.47,111.59,54.51,20.75

[0044] Example 1 1,2-Bis[3,6-bis(4,4'-dimethoxy)diphenylamino-9H-carbazol-9-yl]cyclobutane (see Scheme 1, compound 1 or V1244) [ka]

[0045] A solution of intermediate B (0.5 g, 0.7 mmol, 1 eq) and 4,4'-dimethoxydiphenylamine (0.98 g, 4.3 mmol, 6 eq) in anhydrous toluene (7 mL) was purged with argon for 30 min. Then, palladium(II) acetate (0.02 eq), tri-tert-butylphosphonium tetrafluoroborate (0.027 eq), and sodium tert-butoxide (6 eq) were added, and the solution was refluxed under argon for 5 h. After cooling to room temperature, the reaction mixture was filtered through Celite and extracted with ethyl acetate and distilled water. The organic layer was dried over anhydrous Na2SO4, filtered, and the solvent was evaporated. The crude product was purified by column chromatography using 3:9.5 v / v THF / n-hexane as the eluent. The resulting product was precipitated from acetone with a 15-fold excess of ethanol. The precipitate was filtered and washed with ethanol to collect the product V1244. The precipitated product was recovered as a pale green solid (0.52 g, 56.3% yield).

[0046] 1H NMR(400MHz,THF-d6)δ7.66-7.51(m,8H),7.08(d,J=8.8,1.7Hz,4H),6.88(d,J=8.8Hz,16H), 6.71(d,J=8.8Hz,16H),6.34-6.18(m,2H),3.69(s,24H),3.03-2.91(m,2H),2.70-2.60(m,2H)

[0047] 13 C NMR (101MHz, THF) δ154.95,142.47,141.24,137.03,124.27,124.13,123.92,116.39,114.17,110.55,54.75,54.54,20.62

[0048] Elemental analysis: calculated, %: C 77.88; H 5.76; N 6.49 C 84 H 74 N6O8 Findings, %: C77.97; H5.72; N6.41

[0049] Example 2 1,2-bis[3,6-bis(4,4'-dimethyl)diphenylamino-9H-carbazol-9-yl]cyclobutane (V1296) (see Scheme 1, compound 2 or V1296) [ka]

[0050] A solution of intermediate B (0.5 g, 0.7 mmol, 1 eq) and 4,4'-dimethoxydiphenylamine (0.84 g, 4.3 mmol, 6 eq) in anhydrous toluene (7 mL) was purged with argon for 30 min. Palladium(II) acetate (0.02 eq), tri-tert-butylphosphonium tetrafluoroborate (0.027 eq), and sodium tert-butoxide (6 eq) were then added, and the solution was refluxed under argon for 22 h. After cooling to room temperature, the reaction mixture was filtered through Celite and extracted with ethyl acetate and distilled water. The organic layer was dried over anhydrous Na2SO4, filtered, and the solvent was evaporated. The crude product was recrystallized from ethanol / toluene 1:1 to give V1296 as pale green crystals (0.46 g, 55.4% yield). 1 H NMR(400MHz,THF-d6)δ7.67(s,4H),7.66(d,J=8.8Hz,4H),7.12(d,J=8.8Hz,4H),6.93(d,J=8.4Hz, 16H),6.85(d,J=8.4Hz,16H),6.39-6.25(m,2H),3.09-2.92(m,2H),2.79-2.59(m,2H),2.22(s,24H)

[0051] 13 C NMR (101MHz, THF) δ144.59,138.67,135.70,128.59,127.45,123.16,122.52,120.71,116.07,108.91,52.89,18.84,17.92

[0052] Elemental analysis: calculated values, %: C 86.41, H 6.39, N 7.20 C 84 H 74 N6 Found values, %: C86.24, H6.45, N7.31

[0053] Example 3 1,2-Bis(3,6-bisdiphenylamino-9H-carbazol-9-yl)cyclobutane (see Scheme 1, compound 3 or V1297) [ka]

[0054] A solution of intermediate B (0.5 g, 0.7 mmol, 1 eq) and diphenylamine (0.72 g, 4.3 mmol, 6 eq) in anhydrous toluene (7 mL) was purged with argon for 30 min. Then, palladium(II) acetate (0.02 eq), tri-tert-butylphosphonium tetrafluoroborate (0.027 eq), and sodium tert-butoxide (6 eq) were added, and the solution was refluxed under argon for 27 h. After cooling to room temperature, the reaction mixture was filtered through Celite and extracted with ethyl acetate and distilled water. The organic layer was dried over anhydrous Na2SO4, filtered, and the solvent was evaporated. The crude product was purified by column chromatography using 1:9 v / v THF / n-hexane as the eluent. The resulting product was precipitated from THF with a 15-fold excess of n-hexane. The precipitate was filtered and washed with hexane, and product V1297 was collected. The precipitated product was recovered as a pale green solid (0.44 g, 58.7% yield).

[0055] 1 H NMR(400MHz,DMSO-d6)δ7.89(d,J=9.2Hz, 4H),7.83(d,J=2.0Hz, 4H),7.27-7.05(m ,20H),6.97-6.79(m,24H),6.39-6.24(m,2H),2.93-2.75(m,2H),2.70-2.55(m,2H)

[0056] 13 C NMR (101MHz, DMSO) δ148.42,139.76,138.02,129.65,126.33,124.09,122.46,122.02,119.67,112.27,54.24,21.65

[0057] Elemental analysis: calculated, %: C 86.50; H 5.54; N 7.96 C 76 H58 N6 Findings, %: C 86.65; H 5.50; N 7.85

[0058] Example 4 1,2-bis{3,6-bis[N-(9,9-dimethylfluoren-2-yl)-N-(4-methoxyphenyl)amino]-9H-carbazol-9-yl}cyclobutane (compound 4 or V1361) [ka]

[0059] A solution of intermediate B (0.5 g, 0.7 mmol, 1 eq) and N-(4-methoxydiphenyl)-9,9-dimethyl-9H-fluoren-2-amine (1.35 g, 4.3 mmol, 6 eq) in anhydrous toluene (10 mL) was purged with argon for 30 min. Palladium(II) acetate (0.02 eq), tri-tert-butylphosphonium tetrafluoroborate (0.027 eq), and sodium tert-butoxide (6 eq) were then added, and the solution was refluxed under argon for 5 h. After cooling to room temperature, the reaction mixture was filtered through Celite and extracted with ethyl acetate and distilled water. The organic layer was dried over anhydrous Na2SO4, filtered, and the solvent was evaporated. The crude product was purified by column chromatography using 5.5:19.5 v / v THF / n-hexane as the eluent. The resulting product was precipitated from THF with a 15-fold excess of n-hexane. The precipitate was filtered and washed with hexane to collect the product V1361 as a yellow-green solid (0.67 g, 57.3% yield).

[0060] 1H NMR(400MHz,DMSO-d6)δ7.88(d,J=8.4Hz,4H),7.78(s,4H),7.55(d,J=7.8Hz,4H),7 .49(d,J=7.8Hz,4H),7.28(d,J=7.2Hz,4H),7.24-7.16(m,8H),7.11(t,J=7.4Hz,4H ),7.00(d,J=8.6Hz,8H),6.93(s,4H),6.80(d,J=8.6Hz,8H),6.69(d,J=8.4Hz,4H), 6.42-6.23(m,2H),3.64(s,12H),2.92-2.77(m,2H),2.76-2.56(m,2H),1.17(s,24H)

[0061] 13 C NMR (101MHz, DMSO) δ155.83,154.82,153.15,149.03,141.15,140.42,139.09,137.50,131.40,127.37,126.76,126.35 ,125.32,123.94,122.86,121.12,119.41,119.19,118.17,115.27,114.25,111.87,55.55,53.96,46.56,27.29,27.25

[0062] Elemental analysis: calculated, %: C 84.95; H 6.02; N 5.12 C 116 H 98 N6O2 Findings, %: C84.85; H6.06; N5.15

[0063] Example 5 1,2-bis{3,6-bis[N-(9-ethylcarbazol-3-yl)-N-(4-methoxyphenyl)amino]-9H-carbazol-9-yl}cyclobutane (compound 5 or V1366) [ka]

[0064] A solution of intermediate B (0.5 g, 0.7 mmol, 1 eq) and 9-ethyl-N-(4-methoxyphenyl)-9H-carbazol-3-amine (1.35 g, 4.3 mmol, 6 eq) in anhydrous toluene (10 mL) was purged with argon for 30 min. Then, palladium(II) acetate (0.02 eq), tri-tert-butylphosphonium tetrafluoroborate (0.027 eq), and sodium tert-butoxide (6 eq) were added, and the solution was refluxed under argon for 5 h. After cooling to room temperature, the reaction mixture was filtered through Celite and extracted with ethyl acetate and distilled water. The organic layer was dried over anhydrous Na2SO4, filtered, and the solvent was evaporated. The crude product was purified by column chromatography using 4.5:8 v / v THF / n-hexane as the eluent. The resulting product was precipitated from THF with a 15-fold excess of n-hexane. The precipitate was filtered and washed with hexane to collect the product V1366 as a yellow-green solid (0.71 g, 60.7% yield).

[0065] 1 H NMR(400MHz,THF-d6)δ7.84(d,J=8.0Hz,4H),7.75(s,4H),7.69-7.58(m,8H),7. 37(d,J=8.4Hz,4H),7.33-7.25(m,8H),7.19-7.11(m,8H),6.97(t,J=7.4Hz,4H), 6.92(d,J=8.8Hz,8H),6.68(d,J=8.8Hz,8H),6.38-6.26(m,2H),4.31(q,J=7.0Hz ,8H),3.65(s,12H),3.08-2.93(m,2H),2.71-2.58(m,2H),1.33(t,J=7.0Hz,12H)

[0066] 13C NMR (101MHz, THF) δ154.55,143.30,141.94,141.50,140.44,136.86,136.20,125.19,124.98,124.35,123.79,123.69 ,123.56,122.77,120.21,118.13,116.09,115.97,114.11,110.49,108.88,108.19,54.74,54.52,37.04,20.57,13.14

[0067] Elemental analysis: calculated, %: C 81.82; H 5.76; N 8.52 C 112 H 94 N 10 O4 Findings, %: C 81.91; H 5.70; N 7.50

[0068] Example 6 1,2-Bis{3,6-bis[N,N-bis(9-ethylcarbazol-3-yl)amino]-9H-carbazol-9-yl}cyclobutane (compound 6 or V1367) [ka]

[0069] A solution of intermediate B (0.5 g, 0.7 mmol, 1 eq) and bis(9-ethyl-9H-carbazol-3-yl)amine (1.72 g, 4.3 mmol, 6 eq) in anhydrous toluene (12 mL) was purged with argon for 30 min. Then, palladium(II) acetate (0.02 eq), tri-tert-butylphosphonium tetrafluoroborate (0.027 eq), and sodium tert-butoxide (6 eq) were added, and the solution was refluxed under argon for 6 h. After cooling to room temperature, the reaction mixture was filtered through Celite and extracted with ethyl acetate and distilled water. The solid precipitate obtained from the extraction was filtered. The crude product was purified by column chromatography using 4.5:8 v / v THF / n-hexane as the eluent. The resulting product was precipitated from THF with a 15-fold excess of ethanol. The precipitate was filtered and washed with ethanol to collect V1367 as a yellow-green solid (0.62 g, 43.7% yield).

[0070] 1 H NMR(400MHz,THF-d6)δ7.92-7.50(m,24H),7.38-7.10(m,36H),6.93(t,J=7.4Hz,8H),6.46-6. 29(m,2H),4.24(q,J=6.8Hz,16H),3.11-2.94(m,2H),2.70-2.57(m,2H),1.28(t,J=6.8Hz,24H)

[0071] 13 C NMR (101MHz, THF) δ142.76,142.40,140.41,136.70,135.94,128.72,127.96,125.07,124.46,123. 66,123.32,122.85,120.24,118.04,115.74,115.44,110.45,108.83,108.10,54.73,37.01,13.17

[0072] Elemental analysis: calculated, %: C 84.39; H 5.77; N 9.84 C 140 H 114 N14 Findings, %: C 84.28; H 5.83; N 9.89

[0073] Example 7 1,2-Bis|3,6-bis{4-[N,N-bis(4-methoxyphenyl)amino]phenyl}-9H-carbazol-9-yl|cyclobutane (see Scheme 2, compound 7 or V1321) [ka]

[0074] A solution of intermediate B (0.1 g, 0.14 mmol, 1 eq) and 4-methoxy-N-(4-methoxyphenyl)-N-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)aniline (0.61 g, 1.4 mmol, 10 eq) in anhydrous THF (10 mL) was purged with argon for 10 min. Then, tetrakis(triphenylphosphine)palladium(0) (0.115 eq) and 2 M K2CO3 (4 mL) were added, and the solution was heated at 90 °C for 3 h. After cooling to room temperature, the reaction mixture was filtered through Celite and extracted with ethyl acetate and distilled water. The organic layer was dried over anhydrous Na2SO4, filtered, and the solvent was evaporated. The crude product was purified by column chromatography using 4:8.5 v / v THF / n-hexane as the eluent. The resulting product was precipitated from THF with a 15-fold excess of n-hexane. The precipitate was filtered and washed with hexane to collect the product V1321 as a yellow-green solid (0.1 g, 43.9% yield).

[0075] 1H NMR(400MHz,THF-d6)δ8.34(s,4H),7.76(d,J=8.8Hz,4H),7.59(d,J=8.8Hz,4H),7.51(d,J=8.6Hz,8H),7.02(d,J=8.8Hz, 16H),6.97(d,J=8.6Hz,8H),6.82(d,J=8.8Hz,16H),6.50-6.35(m,2H),3.74(s,24H),3.19-3.02(m,2H),2.86-2.68(m,2H)

[0076] 13 C NMR (101MHz, THF) δ154.17,145.70,139.26,137.80,132.26,130.62,125.34, 124.20,122.65,122.48,119.37,115.94,112.55,108.21,52.85,52.74,18.86

[0077] Elemental analysis: calculated, %: C 81.08; H 5.67; N 5.25 C 108 H 90 N6O8 Findings, %: C 81.35; H 5.54; N 5.23 Example 8 Ionization potential measurement

[0078] The solid-state ionization potential (I p ) was measured by electron photoemission in air method (E. Miyamoto, Y. Yamaguchi, M. Masaaki, Electrophotography, 1989, vol. 28, pp. 364). Samples for ionization potential measurements were prepared by dissolving the material in THF and coated on an Al plate precoated with a methyl methacrylate and methacrylic acid copolymer adhesive layer of ~0.5 μm thickness. The thickness of the transport material layer was 0.5 -1The wavelength was 1000 nm. Photoelectron spectroscopy experiments are performed in vacuum, and high vacuum is one of the main requirements for these measurements. If the vacuum is not high enough, sample surface oxidation and gas adsorption will affect the measurement results. In our case, however, the investigated organic materials are sufficiently stable to oxygen, and measurements were performed in air. The sample was illuminated with monochromatic light from a quartz monochromator with a deuterium lamp. The power of the incident light beam was (2-5) 10 -8 A negative voltage of -300 V was applied to the sample substrate. 2 A counter electrode with a slit of 10 mm was placed at a distance of 8 mm from the sample surface for illumination. The counter electrode was connected to the input of a BK2-16 type electrometer operating in open input mode for photocurrent measurements. -15 -10 -12 A photocurrent of magnitude A flows through the circuit under illumination. The photocurrent I strongly depends on the photon energy hν of the incident light. I 0.5 = f(hν) dependence is plotted. Usually, the dependence of the photocurrent on the incident photon energy is I near the threshold. 0.5 The linear part of this dependence is extrapolated to the hν axis, and I p The value is determined as the photon energy at the intercept point. p The results are shown in Table 1. Example 9 Hole drift mobility measurements

[0079] Samples for hole transport measurements were prepared by spin-coating THF solutions of the synthesized compounds 1-7 or their compositions with bisphenol-Z polycarbonate (PC-Z) (Iupilon Z-200, Mitsubishi Gas Chemical Co., Ltd.) in a 1:1 weight ratio onto a polyester film with a conductive Al layer. THF was used for compounds 1-7. Layer thicknesses ranged from 5-10 μm. Hole drift transport was measured by xerographic time-of-flight (XTOF) (Vaezi-Nejad, SM, Int. J. Electronics, 1987, 62, No. 3, 361-384). An electric field was generated by a positive corona charge. Charge carriers were generated at the layer surface by illumination with a nitrogen laser pulse (pulse duration 2 ns, wavelength 337 nm). The layer surface potential decrease as a result of pulsed illumination was less than 1-5% of the starting potential before illumination. A capacitance probe connected to a broad-frequency electrometer measured the speed of surface charge decay dU / dt. The transit time t t was determined by the kink on the temporal dU / dt curve on a log-log scale. The drift mobility is given by the equation μ = d 2 / U0t t where d is the layer thickness and U0 is the surface potential at the moment of illumination. The results for μ are shown in Table 1.

[0080] Table 1. Ionization potentials (I p ) and charge mobility value (μ) [Table 1] [Table 2] [Table 3]

[0081] Estimated I of synthesized compounds 1, 5, and 6 pThe values ​​range from 4.77 eV to 5.03 eV, which is close to that of spiro-OMeTAD (5.0 eV). p The values ​​are slightly higher, ranging from 5.28 to 5.48 eV. The measured charge mobility values ​​of synthesized compounds 1 and 3-7 are also comparable to those of spiro-OMeTAD, while the charge mobility of compound 2 increases by approximately one order of magnitude in weak electric fields (μ = 10 -4 cm 2 V -1 S -1 ). Example 10 Photovoltaic cell manufacturing and performance measurement

[0082] The performance of hole-transporting compounds 1-7 was tested in mixed perovskite-based solar cells using a mesoporous TiO2 photoanode and an Au cathode (FTO / compact TiO2 / mesoporous compact TiO2 / mixed perovskite / V1244 / Au).

[0083] The perovskite solar cells were prepared as follows. Chemically etched FTO glass (Nippon Sheet Glass) was cleaned with detergent, acetone, and isopropanol. The substrate was coated with a thin layer of SnO nanoparticles from a commercially available aqueous solution at 3000 rpm to 1500 rpm s for 30 s. -1 The SnO2 solution was spin-coated in an increasing amount, with the weight ratio of SnO2 solution to water being 1:3. After spin-coating, the substrate was immediately dried on a hotplate at 80 °C, and then heated at 190 °C for 30 min. After cooling, 1.5 M (FAPbI3) 0.85 (MAPbBr3) 0.15A perovskite precursor solution was prepared by mixing PbI2, PbBr2, MABr, and FAI in a DMSO / DMF mixed solvent (1 / 8). The perovskite solution was then spin-coated onto the substrate at 1000 rpm for 10 seconds and 5000 rpm for 30 seconds, respectively. 1 ml of diether was then added dropwise at 5000 rpm for 10 seconds. The perovskite film was annealed at 100 °C for 40 minutes. A reference solution was prepared by dissolving 91 mg of spiro-OMeTAD (Merck) in 1 mL of chlorobenzene with additives. As additives, 21 μL of Li-bis(trifluoromethanesulfonyl)imide (520 mg in 1 mL of acetonitrile) from a stock solution, 16 μL of FK209 [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)-cobalt(III), tris(bis(trifluoromethylsulfonyl)imide)] (375 mg in 1 mL of acetonitrile), and 36 μL of 4-tert-butylpyridine were added. A solution of the cyclobutyl-based hole-transporting compounds 1-7 was prepared by dissolving the synthesized compounds in 1 mL of chlorobenzene at an optimized concentration of 40 mM with the additives. As additives, 15 μL of Li-bis(trifluoromethanesulfonyl)imide from a stock solution, 10 μL of FK209, and 26 μL of 4-tert-butylpyridine were added. The HTM layer was formed by spin-coating the solution at 4000 rpm for 20 seconds, followed by thermal evaporation deposition of a 70 nm thick Au electrode. All preparation work for the perovskite and HTM deposition was carried out in a nitrogen-filled glovebox to minimize the effects of moisture.

[0084] The current-voltage characteristics were recorded by applying an external potential bias to the cell while the generated photocurrent was recorded by a digital source meter (Keithley Model 2400). The light source was a 450 W xenon lamp (Oriel) equipped with a Schott K113 Tempax solar filter (Praezisions Glas & Optik GmbH) to match the lamp's emission spectrum to the AM1.5G standard. Before each measurement, the exact light intensity was determined using a calibrated Si reference diode equipped with an infrared-blocking filter (KG-3, Schott). The voltage scan rate was 100 mV s -1 No preconditioning of the device, such as light soak or long-term applied forward voltage bias, was applied before the start of the measurements. The cell had a fixed active area of ​​0.891 cm to reduce the effect of scattered light due to the small size of the device. 2 masked with an active area of

[0085] The performance characterization results are shown in Table 2. Figure 2 shows typical current density-voltage (JV) curves (reverse scan) for PSCs with spiro-OMeTAD, compound 1 (V1244), compound 7 (V1321), and compound 5 (V1366) as references. Devices with cyclobutyl-based HTMs, especially compound 5 (V1366), exhibit higher photocurrents and comparable photoelectric conversion performance to spiro-OMeTAD. However, devices with compounds 2 (V1296), 3 (V1297), 4 (V1361), and 6 (V1367) as cyclobutyl-based HTMs exhibit relatively low PCE (Figure 3). Such degraded performance of compounds 2 (V1296) and 3 (V1297) can be explained by their very deep HOMO levels, which may result in a mismatch with the perovskite valence band, while compound 6 (V1367) has one of the lowest hole drift mobilities in this series, at 24.17 mA cm. -2 J SC , V of 1.114V OC, and 24.38 mA·cm compared to 21.64% for spiroOMeTAD with a FF of 80.3%. -2 J SC , an open circuit voltage of 1.092 V, and a PCE of 21%, consisting of an FF of 79.1%, were achieved for compound 5 (V1366)-based devices, demonstrating that molecular engineering of the side arm fully defines the performance of the final device. Table 2 Photovoltaic performance compounds 1-7 and spiro-OMeTAD [Table 4] Example 11 Perovskite solar cell module fabrication and performance measurement

[0086] The performance of hole-transporting compound 5 (V1366) as an HTM in perovskite solar cell modules was compared with modules using the standard HTM, spiro-OMeTAD.

[0087] Modules consisting of cells with eight strips connected in series were scribed using a Newport YAG laser. For the fabrication of solar cell modules, 6.5 cm × 7 cm FTO substrates were patterned by the laser with a power of 1500 mW and a scribe width of 80 μm. The substrates were then scribbled with a thin layer of SnO2 nanoparticle film from a commercially available aqueous solution at 3000 rpm to 1500 rpm s for 30 seconds. -1 The weight ratio of SnO2 solution to water was 1:3. After spin-coating, the substrate was immediately dried on a hotplate at 80 °C, and then heated to 190 °C for 30 min. After cooling, 1 M (FAPbI3) 0.85 (MAPbBr3) 0.15A perovskite precursor solution was prepared by mixing PbI2, PbBr2, MABr, and FAI in a DMSO / DMF mixed solvent (1 / 4). The perovskite solution was then spin-coated onto the substrate at 1000 rpm for 10 seconds and 4000 rpm for 30 seconds, respectively. 600 μL of chlorobenzene was added dropwise at 4000 rpm for 10 seconds. The perovskite film was annealed at 100 °C for 40 minutes. A solution of compound 5 (V1366)HTM was prepared by dissolving 40 mM V1366 in 1 mL of chlorobenzene with additives. 15 μL of Li-bis(trifluoromethanesulfonyl)imide from the stock solution, 10 μL of FK209, and 26 μL of 4-tert-butylpyridine were added as additives. The HTM layer was formed by spin-coating the solution at 4000 rpm for 30 seconds, followed by thermal evaporation deposition of a 70 nm thick Au electrode. Next, the SnO2 / perovskite / HTM layer was scribed with a laser with 1000 mW power and a 500 μm scribe width. Finally, the gold electrode was deposited by thermal evaporation, and the gold layer was scribed with a laser with 1000 mW power and a 100 μm scribe width. The characterization of the modules was performed similarly to photovoltaic cells with the following modifications: the active area of ​​each module was counted using Nano Mesurer 1.2. The IPCE spectrum was ≈10 mW cm , provided by an array of white light-emitting diodes. -2 The signal was recorded as a function of wavelength under a constant white light bias of 100 Hz. The excitation beam coming from a 300 W xenon lamp (ILC Technology) was focused by a Gemini-180 double monochromator (Jobin Yvon Ltd) and chopped at ≈2 Hz. The signal was recorded using a Model SR830 DSP Lock-In Amplifier (Stanford Research Systems). All measurements were characterized at room temperature in air. To characterize the enhanced performance of cyclobutyl-based HTMs, we fabricated a 6.5 × 7 cm sized perovskite module based on compound 5 (V1366). The module delivered 2.99 mA cm -2 J SC , V of 8.275V OC , and exhibits a PCE of 19.06% with an FF of 77%. To the best of our knowledge, a PCE value of over 19% is the highest reported PCE to date for a non-spiro OMeTAD-based perovskite module.

[0088] References 1.Y.Rong,Y.Hu,A.Mei,H.Tan,MISaidaminov,S.II.Seok,MDMcGehee,EHSargent,EH;Han,H.Science 2018, 361, No.eaat8235.1 2. A. Kojima, K. Teshima, Y. Shirai, T. Miyasaka. J. Am. Chem. SoC. 2009, 131, 6050-6051. 3.Y.Shi,K.Hou,Y.Wang,K.Wang,HCRen,MYPang,F.Chen,S.Zhang,J.Mater.Chem.A,2016,4,5415-5422. 4. TPISaragi, T. Spehr, A. Siebert, T. Fuhrmann-Lieker, J. Salbeck, Chem. Rev., 2007, 107, 1011-1065. 5. H. Jiang, J. Sun, J. Zhang, Curr.org.Chem.2012,16,2014. 6. Z. Chen, H. Li, X. Zheng, Q. Zhang, Z. Li, Y. Hao, G. 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Tsutsumi, M. Yamamoto, Y. Nishijima, J. Polym. Sci. Part B Polym. Phys. 1987, 25, 2139. 17.T.Sasakawa,T.Ikeda,S.Tazuke,J.Appl.Phys.1989,65,2750. 18. T. Ikeda, H. Mochizuki, Y. Hayashi, M. Sisido, T. Sasakawa, J. Appl. Phys. 1991, 70, 3689. (Other possible items) [Item 1] A photovoltaic cell comprising a conductive support layer, a surface-enhanced deposit layer, a photosensitive layer, a hole transport layer, and a counter electrode, wherein the hole transport layer comprises a cyclobutane-based hole transport compound. [Item 2] the cyclobutane-based hole transport compound is [ka] is a compound of formula (I) comprising R, R 1 is a monocyclic or polycyclic ring system containing at least one pair of conjugated double bonds (-C=CC=C-), said polycyclic ring system containing fused aromatic rings or monocyclic aromatic rings bonded together by a covalent bond, or forming a heteroaromatic system with N, O, S, Se, Si heteroatoms, said monocyclic or polycyclic ring system being substituted with H, halogen, cyano, C1-C20 cyanoalkyl, C1-C20 alkyl, C1-C20 alkoxy, C1-C20 alkoxyalkyl, C1-C20 haloalkyl, C1-C20 haloalkoxyalkyl, C4-C20 aryl, C4-C20 alkylaryl, C4-C20 alkoxyaryl, C4-C20 alkenylalkylaryl, C4-C20 alkoxyarylalkenyl, or C4-C20 bisalkoxyarylalkenyl; the cyanoalkyl group, alkyl group, alkoxy group, alkoxyalkyl group, haloalkyl group, haloalkoxyalkyl group, C4-C20 aryl group, C4-C20 alkylaryl group, C4-C20 alkoxyaryl group, C4-C20 alkenyl alkylaryl group, C4-C20 alkoxyaryl alkenyl group, or C4-C20 bisalkoxyaryl alkenyl group may be linear, branched, or cyclic; halogen is selected from Cl, F, Br and I; Item 1. The photovoltaic cell according to item 1. [Item 3] the cyclobutane-based hole transport compound is 1,2-bis[3,6-bis(4,4'-dimethoxy)diphenylamino-9H-carbazol-9-yl]cyclobutane, 1,2-bis{3,6-bis[N-(9-ethylcarbazol-3-yl)-N-(4-methoxyphenyl)amino]-9H-carbazol-9-yl}cyclobutane, and 1,2-Bis|3,6-bis{4-[N,N-bis(4-methoxyphenyl)amino]phenyl}-9H-carbazol-9-yl|cyclobutane Item 2. The photovoltaic cell according to item 1, selected from: [Item 4] 3. The photovoltaic cell according to item 2, wherein the photovoltaic cell is an organic photovoltaic cell, a photovoltaic solid state cell, or a dye-sensitized solar cell. [Item 5] 3. The photovoltaic cell of item 2, further comprising an organic-inorganic perovskite as a photosensitizer. [Item 6] The organic-inorganic perovskite has a perovskite structure of formula (II): AMX3(II) A is Li + , Na + , K. + , Rb + , Cs +an organic monovalent cation selected from the group consisting of an ammonium ion, an ammonium ion, and an amidinium ion, wherein one or more hydrogen atoms of the ammonium ion or the amidinium ion are substituted with an alkyl group, an acyl group, or a halogen, and the ammonium ion is a mono-, di-, tri-, or tetra-alkylammonium ion, wherein the substituted alkyl groups are independently selected from C1-C6; M is Cu 2+ , Ni 2+ , Co 2+ , Fe 2+ , Mn 2+ , Cr 2+ , Pd 2+ , Cd 2+ , Ge 2+ , Sn 2+ , Pb 2+ ,EU 2+ , and Yb 2+ a divalent metal cation selected from the group consisting of X is Cl - , Br - , I - , N.C.S. - , C.N. - , and N.C.O. - are monovalent anions independently selected from Item 5. The photovoltaic cell according to item 5. [Item 7] The organic-inorganic perovskite has a mixed perovskite structure according to formula (III): A 1 1-y A 2 y PbX 1 3-z X 2 z (III) A 1 and A 2 Li + , Na + , K. + , Rb + , Cs +an organic monovalent cation independently selected from the group consisting of an ammonium ion, an ammonium ion, and an amidinium ion, wherein one or more hydrogen atoms of the ammonium ion or the amidinium ion are substituted with an alkyl group, an acyl group, or a halogen, and the ammonium ion is a mono-, di-, tri-, or tetra-alkylammonium ion, wherein the substituted alkyl group is independently selected from C1-C6; X 1 and X 2 is Cl - , Br - , I - , N.C.S. - , C.N. - , and N.C.O. - are the same or different monovalent anions selected from y is in the interval between 0.1 and 0.9, z is in the interval between 0.2 and 2, Item 5. The photovoltaic cell according to item 5. [Item 8] A is a methylammonium ion or a formamidium ion, and X is Br - or I - 7. The photovoltaic cell according to item 6, wherein [Item 9] A 1 is methylammonium ion, A 2 is the formamidium ion, X 1 Br - , and X 2 I - 8. The photovoltaic cell according to item 7, wherein [Item 10] 3. The photovoltaic cell of item 2, wherein the surface-enhanced deposition layer comprises Si, TiO2, SnO2, Fe2O3, ZnO, WO3, Nb2O5, CDS, ZnS, PbS, Bi2S3, CdSe, CdTe, SrTiO3, GaP, InP, GaAs, CuInS2, CuInSe2, or a combination thereof. [Item 11] 3. The photovoltaic cell of item 2, wherein the hole transport layer further comprises one or more of Li-bis(trifluoromethanesulfonyl)imide, tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)-cobalt(III), tris(bis trifluoromethylsulfonyl)imide, and 4-tert-butylpyridine. [Item 12] 3. The photovoltaic cell of item 2, wherein the conductive support layer comprises a conductive material selected from indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), ZnO—Ga2O3, ZnO—Al2O3, tin oxide, antimony-doped tin oxide (ATO), SrGeO3, and zinc oxide. [Item 13] Item 13. The photovoltaic cell according to item 12, further comprising a transparent substrate added on top of the conductive material. [Item 14] Item 3. The photovoltaic cell of item 2, wherein each layer is configured to have a planar structure. [Item 15] 3. The photovoltaic cell of item 2, wherein the conductive support layer is next to the surface-enhanced deposit layer, the surface-enhanced deposit layer is between the conductive support layer and the photosensitive layer, the photosensitive layer is between the surface-enhanced deposit layer and the hole transport layer, and the hole transport layer is between the photosensitive layer and the counter electrode. [Item 16] 16. A photovoltaic device comprising two or more photovoltaic cells according to any one of items 2 to 15, wherein the photovoltaic cells are electrically connected in series or in parallel.

Claims

1. 1. A photovoltaic cell comprising a conductive support layer, a surface-enhanced deposition layer, a photosensitive layer, a hole transport layer, and a counter electrode, wherein the hole transport layer comprises a cyclobutane-based hole transport compound; the cyclobutane-based hole transport compound is 【Chemistry 40】 A compound of formula (I) comprising: R is H, R １ is a diarylamino group, a carbazol-9-yl group, a 3,6-dimethylcarbazol-9-yl group, or a 3,6-dimethoxycarbazol-9-yl group, The photovoltaic cell, wherein the diarylamino group has any combination of aryl groups selected from a 4-methoxyphenyl group and a 9,9-dimethylfluoren-2-yl group, two 9,9-dimethylfluoren-2-yl groups, two 9-ethylcarbazol-3-yl groups, two 9-ethylcarbazol-2-yl groups, a 9-ethylcarbazol-2-yl group and a 9-ethylcarbazol-3-yl group, a 9,9-dimethylfluoren-3-yl group and a 4-methoxyphenyl group, or a 9,9-dimethylfluoren-2-yl group and a 9,9-dimethylfluoren-3-yl group.

2. R １ is a diarylamino group, 2. The photovoltaic cell according to claim 1, wherein the diarylamino group has a combination of any one aryl group selected from a 4-methoxyphenyl group and a 9,9-dimethylfluoren-2-yl group, or two 9-ethylcarbazol-3-yl groups.

3. The photovoltaic cell of claim 1 , wherein the photovoltaic cell is an organic photovoltaic cell, a photovoltaic solid state cell, or a dye-sensitized solar cell.

4. 10. The photovoltaic cell of claim 1, further comprising an organic-inorganic perovskite as a photosensitizer.

5. The organic-inorganic perovskite has a perovskite structure of formula (II): AMX ３ (II) A is Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , an ammonium ion, or an amidinium ion, wherein one or more hydrogen atoms of the ammonium ion or amidinium ion are substituted with an alkyl group, an acyl group, or a halogen, and the ammonium ion is a mono-, di-, tri-, or tetra-alkylammonium ion, wherein the substituted alkyl group is independently selected from C1-C6; M is Cu ２＋ , Ni ２＋ , Co ２＋ , Fe ２＋ , Mn ２＋ , Cr ２＋ , Pd ２＋ , Cd ２＋ , Ge ２＋ , Sn ２＋ , Pb ２＋ , Eu ２＋ , and Yb ２＋ a divalent metal cation selected from the group consisting of X is Cl － ,Br － , I － , N.C.S. － , C.N. － , and NCO － are monovalent anions independently selected from The photovoltaic cell of claim 4.

6. The organic-inorganic perovskite has a mixed perovskite structure according to formula (III): A １ １－ｙ A ２ ｙ PbX １ ３－ｚ X ２ ｚ (III) A １ and A ２ Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , an ammonium ion, or an amidinium ion, wherein one or more hydrogen atoms of the ammonium ion or the amidinium ion are substituted with an alkyl group, an acyl group, or a halogen, and the ammonium ion is a mono-, di-, tri-, or tetra-alkylammonium ion, wherein the substituted alkyl group is independently selected from C1-C6; X １ and X ２ is Cl － ,Br － , I － , N.C.S. － , C.N. － , and NCO － are the same or different monovalent anions selected from y is in the interval between 0.1 and 0.9, z is in the interval between 0.2 and 2, The photovoltaic cell of claim 4.

7. A is a methylammonium ion or a formamidium ion, and X is Br － or I － 6. The photovoltaic cell of claim 5, wherein:

8. A １ is methylammonium ion, A ２ is formamidium ion, X １ HaBr － , and X ２ is I － 7. The photovoltaic cell of claim 6, wherein:

9. The surface-increasing adhesion layer is made of Si, TiO ２ , SnO ２ , Fe ２ O ３ , ZnO, WO ３ , Nb ２ O ５ , CDS, ZnS, PbS, Bi ２ S ３ , CdSe, CdTe, SrTiO ３ , GaP, InP, GaAs, CuInS ２ , CuInSe ２ 10. The photovoltaic cell of claim 1, comprising:

10. 10. The photovoltaic cell of claim 1, wherein the hole transport layer further comprises one or more of Li-bis(trifluoromethanesulfonyl)imide, tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)-cobalt(III), tris(bis trifluoromethylsulfonyl)imide, and 4-tert-butylpyridine.

11. The conductive support layer is made of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), ZnO—Ga ２ O ３ , ZnO-Al ２ O ３ , tin oxide, antimony-doped tin oxide (ATO), SrGeO ３ 10. The photovoltaic cell of claim 1, comprising a conductive material selected from:

12. The photovoltaic cell of claim 11 , further comprising a transparent substrate added over the conductive material.

13. The photovoltaic cell of claim 1 , wherein each layer is configured to have a planar structure.

14. 10. The photovoltaic cell of claim 1, wherein the conductive support layer is next to the surface-enhanced deposit layer, the surface-enhanced deposit layer is between the conductive support layer and the photosensitive layer, the photosensitive layer is between the surface-enhanced deposit layer and the hole transport layer, and the hole transport layer is between the photosensitive layer and the counter electrode.

15. 1. A photovoltaic cell comprising a conductive support layer, a surface-enhanced deposition layer, a photosensitive layer, a hole transport layer, and a counter electrode, wherein the hole transport layer comprises a cyclobutane-based hole transport compound; the cyclobutane-based hole transport compound is A photovoltaic cell which is 1,2-bis{3,6-bis[N-(9,9-dimethylfluoren-2-yl)-N-(4-methoxyphenyl)amino]-9H-carbazol-9-yl}cyclobutane.

16. 16. A photovoltaic device comprising two or more photovoltaic cells according to any one of claims 1 to 15, said photovoltaic cells being electrically connected in series or in parallel.

17. A method for producing a photovoltaic cell, comprising producing the photovoltaic cell according to any one of claims 1 to 15.

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