Low-temperature sequential deposition for efficient inverted perovskite solar cells
Mengjiong Chen, Zhenzhen Qin, Ziyang Zhang, Wenxiang Xiang, Yingming Liu, Chuang Tian, Siyuan Chen, Yanbo Wang, Liyuan Han
Abstract
Inverted perovskite solar cell has made significant progress in recent years. Although two-step sequential deposition shows the benefits to obtain higher quality large-size perovskite crystals, the high annealing temperature, which is required to achieve phase transition, leads to the desorption of self-assembled molecules at the buried interface and induces redundant lead iodide at the top interface. Here, we propose a low temperature sequential deposition method by introduce a tailor-made 3-ethyl-1-methyl-1H-imidazol-3-ium dimethyl phosphate into lead iodide precursor solution to facilitate the sufficient reaction between lead iodide and organic salts, and lower the energy barrier from delta- to alpha-perovskite. As a result, highly crystallized and pure alpha-phase perovskite films with large grain size are fabricated, preventing the damage to buried self-assembled molecules and the formation of redundant lead iodide, which contributes to a high open circuit voltage of 1.21 V and a certified efficiency of 26.0%. The encapsulated devices show improved stability following ISOS-D-3 and ISOS-L-2 protocols. The high annealing temperature in two-step sequential deposition could lead to the desorption of self-assembled molecules at the buried interface. Here, the authors propose a low temperature sequential deposition method and achieve certified efficiency of 26.0% for perovskite solar cells.