[20a-PB2-1~59] 12.5 Organic solar cells

[20a-PB2-20] Annealing temperature dependence of a mesoporous layer with highly crystalline fine TiO₂ particles used for low temperature perovskite solar cells

〇Tsuyoshi Abe¹, Masashi Ikegami¹, Tsutomu Miyasaka¹ (1.Toin Univ. of Yokohama)

Keywords:perovskite solar cell, low temperature coating, titanium oxide

In the last decade, lead halide perovskite solar cells have attracted considerable attention, and their energy conversion efficiency increased up to 23% in 2019 from 3.8% in 2009. The fabrication process is solution-based, and the perovskite layer annealing temperature is approximately 100 °C. Therefore, flexible plastic films can be used as substrates. However, typically, a TiO2 layer is required for the electron transport layer in perovskite solar cells, and fabrication of the TiO2 layer requires a high temperature sintering process, which is not compatible with plastic substrates. Therefore, low temperature processes are needed to produce an electron transport layer. In this study, we attempted to prepare an electron transport layer based on metal oxides, such as SnO2 and TiO2, using a low temperature sintering process. The selected parameters, such as the particle size of metal oxides, dispersion solvent, and solvent additives, can lower the process temperature.In this study, to prepare the electron transport layer using a low temperature process, highly crystalline TiO2 nanoparticles with a size of 7 nm and a surface area of 300 m2/g were used. It is expected that high surface area will promote particle necking even at low temperature. In addition, SnO2 dispersion was added, which is used as an electron transport layer in low temperature processes. CH3NH3PbI3 perovskite was used as a light-absorbing layer. Using a general approach, it was deposited on the substrate coated with SnO2, TiO2, or SnO2/TiO2.Two annealing temperatures (i.e., 100 and 150 °C) were evaluated for the preparation of a metal oxide electron selective layer. It was determined that even at 100 °C, the SnO2/TiO2 combined electron transport layer offered a relatively high energy conversion efficiency of 15%.