Perovskite/TiO₂ Interface Passivation Using Poly(vinylcarbazole) and Fullerene for the Photovoltaic Conversion Efficiency of 21%

Abstract

Poly­(vinylcarbazole) (PVCz) dispersed the typical fullerene derivative, PCBM, well in its solution, which was then coated onto a mesoporous titanium oxide (TiO2) layer. PVCz served as a scaffold to fix PCBM homogeneously and to prevent its elution out upon the following perovskite layer formation. A series of perovskite cells were fabricated upon the PVCz/PCBM-modified TiO2 layer. Many of the cells were characterized by a photovoltaic conversion efficiency of >20%, and the top cells had an efficiency of 21.1% (with an average of 21.0%). Fluorescence decay from the perovskite layer of the cell was unchanged with the PVCz/PCBM modification, suggesting an efficient charge transport to the electron-transporting layers. On the other hand, the PVCz/PCBM modification or passivation significantly reduced electroluminescence intensity under an inverse bias application, supporting an efficient suppression of carrier recombination at the TiO2 and perovskite interface.

Anti‐Oxidizing Radical Polymer‐Incorporated Perovskite Layers and their Photovoltaic Characteristics in Solar Cells

“…Perovskite solar cells were fabricated by slightly tuning a previously reported procedure . A compact TiO 2 layer was deposited on the patterned conductive glass substrate of a fluorine‐doped tin oxide (FTO) substrate (Atock, with a sheet resistance of 30 Ω sq −1 ) by spraying an ethanol solution of titanium diisopropoxide bis(acetylacetonate) (Sigma–Aldrich).…”

“…Perovskite solar cells were fabricated by slightly tuning apreviously reported procedure. [5,61] Ac ompact TiO 2 layer was deposited on the patterned conductive glass substrate of af luorine-doped tin oxide (FTO) substrate (Atock, with as heet resistance of 30 W sq À1 ) by spraying an ethanol solution of titanium diisopropoxide bis(acetylacetonate) (Sigma-Aldrich). For the m-TiO 2 underlayer,a ne thanol solution of Ti paste (150 mg mL À1 ,P ST-18NR, JGC Catalysts and Chemicals) was spin coated on the TiO 2 compact layer at 4000 rpm for 20 sf ollowed by immediate annealing at 100 8Cf or 10 min, and annealing at 500 8Cf or 1h.F or the SnO 2 underlayer,aSnO 2 colloidal solution (15 %d ispersion in water,A lfa Aesar), which was diluted with pure water to 1.3 wt %, was spin coated on the TiO 2 compact layer at 3000 rpm for 30 sf ollowed by annealing at 150 8Cf or 30 min.…”

“…[61] PTMA and other polymers (0-1.0 wt %v s. the perovskite) were added as powders to these perovskite precursor solutions and stirred for 1h.T he perovskite solution was spin coated on the m-TiO 2 or planar SnO 2 underlayer at 1000 rpm for 10 st o6 000 rpm for 20 st of orm the perovskite layer.Aformamidine hydrobromide (Tokyo Chemical Industry) solution (5.0 mg mL À1 in 2-propanol) was spin coated at 5000 rpm for 30 st or eform the perovskite layer. [5] PTAA (10 mg in 1mLt oluene, Sigma-Aldrich) with 7.5 mLl ithium bis(trifluoromethylsulfonyl) imide (170 mg mL À1 in acetonitrile, Tokyo Chemical Industry) and 4.0 mL tert-butylpyridine (Tokyo Chemical Industry) was spin-coated at 4000 rpm for 20 so nt he perovskite layer as ah ole-transporting layer.F inally,a100 nm Au layer for the electrode was deposited at 0.1 nm s À1 on the holetransporting polymer layer using av acuum coater under low pressure of < 10 À3 Pa (VPC-1100, ULVAC). The fabricated perovskite cells were kept in ad ry room for ad ay before their performance measurement.…”

“…Organo‐lead halide perovskite solar cells, which consist of light‐harvesting organo‐lead halide perovskite crystals and charge‐transporting layers, have attracted significant attention because of their tremendously improved photovoltaic conversion efficiencies . The cells, for example, fabricated with perovskite compounds using a mixture cations of methylamine, formamidine, cesium, and rubidium have provided high photovoltaic conversion efficiencies of beyond 20 % owing to their wide light absorption and high‐quality perovskite layer formation .…”

“…Organo-lead halide perovskite solar cells, which consist of light-harvesting organo-lead halide perovskite crystalsa nd charge-transportingl ayers,h ave attracted significant attention because of their tremendously improved photovoltaic conversion efficiencies. [1][2][3][4][5][6][7][8][9][10][11][12][13] The cells, for example, fabricated with perovskite compounds using am ixture cations of methylamine, formamidine, cesium, and rubidium have provided high photovoltaic conversion efficiencies of beyond2 0% owing to their wide light absorption and high-quality perovskite layer formation. [14][15][16] Their facile fabrication processes, light weight and possible flexible structures, and low material costs have also led to discussions on replacing conventionals olar cells with these still developing perovskite cells and utilizing them in a tandem configuration.…”