2, National Institute for Materials Science, Tsukuba, , Japan
Recent advances in the use of organic–inorganic hybrid perovskites for optoelectronics have been rapid, with reported power conversion efficiencies of up to 22 per cent for perovskite solar cells. Improvements in stability have also enabled testing over a timescale of thousands of hours. However, large-scale deployment of such cells will also require the ability to produce large-area, uniformly highquality perovskite films. A key challenge is to
overcome the substantial reduction in power conversion efficiency when a small device is scaled up: a reduction from over 20 per cent to about 10 per cent is found when a common aperture area of about 0.1 square centimetres is increased to more than 25 square centimetres. Here we report a new deposition route for methyl ammonium lead halide perovskite films that does not rely on use of a common solvent or vacuum: rather, it relies on the rapid conversion of amine complex precursors to perovskite films, followed by a pressure application step. We disclosed that the molecular interactions between CH3NH3I and CH3NH2 occurred mainly through the interaction between -NH3+ and -NH2.
The deposited perovskite films were highly crystallized, free of pin-holes, highly uniform and had a grain size of 0.8-1.0um, which was 3-4 times larger than that of spin-coating processed films. Importantly, the new deposition approach can be performed in air at low temperatures, facilitating fabrication of large-area perovskite devices. We reached a certified power conversion efficiency of 12.1 per cent with an aperture area of 36.1 square centimetres for a mesoporous TiO2-based perovskite solar module architecture.