Room temperature crystallization and stability of halide perovskite thin films

Abstract

<p indent="0mm">The preparation of metal halide perovskite films with high crystallinity and high stability without heating in air is difficult to be realized, which is important for future large-scale applications of flexible perovskite solar cells. In this paper, we propose a method to realize the crystallization of perovskite thin films at room temperature, by using a mixed solution of three low-boiling polar molecules, 1,2-dimethoxyethane (DME), methylamine (MA), and ethanol (EA). The mixed solution effectively dissolves the perovskite precursor, and high crystallinity perovskite thin films can be prepared without annealing in air. The as-prepared perovskite film still maintains the lattice structure after 120 h of continuous illumination in air, showing high stability under water, oxygen, and illumination conditions. This method is suitable for the preparation of perovskite thin films with a band gap of <sc>1.60–1.78 eV.</sc> Finally, the flexible perovskite solar cells fabricated by this method achieved the highest photoelectric conversion efficiency of 19.63%. This provides a feasible direction for the large-scale commercial production of flexible perovskite solar cells.