Abstract
A novel cryo-controlled nucleation technique is applied to synthesize organometal halide perovskite for solar cells (PSCs). A rapid reduction in the temperature causes a supersaturation condition in the precursor layer, prepared by solution technique, leading to a uniform nucleation sites for the subsequent crystallization phase. The low temperature condition inhibits the pre-mature crystallization of perovskites in the early stage before a uniform seed layer is formed and, thereby, decoupling the nucleation and crystallization phases. This approach allows the formation of a highly uniform nucleation layer and is crucial for the growth of perovskite films with excellent film quality. A power conversion efficiency (PCE) of 21.4 % for the champion PSC was achieved by using this perovskite growth method.