Room temperature crystallization and stability of halide perovskite thin films

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 1.60-1.78 eV. 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.