Two-Step Sequential Deposition of Organometal Halide Perovskite for Photovoltaic Application

Organometal halide perovskite materials have become a superstar in the photovoltaic (PV) field because of their advantageous properties, which boost the power conversion efficiency (PCE) of perovskite solar cells (PSCs) from about 3.8% to above 22% in just seven years. Most importantly, such promising achievement is mainly based on its low-cost and solution-processed fabrication technique. One of the most promising and famous approaches to fabricating perovskite is a two-step sequential deposition method because precursor (e.g., PbI₂) deposition is controllable, versatile, and flexible. Due to tremendous efforts, great progress has been achieved on the two-step sequential deposition method, which helps to promote the development of PSCs. Herein, the progresses on the two-step sequential deposition method of perovskite layers is reviewed thoroughly. At first, the reaction process and principle is introduced and discussed. Then, the research on the deposition techniques, structures, and compositions of precursors (the first step) is presented. Subsequently, the developments on the conversion techniques, conversion solutions, and growth of large crystals at the second step are introduced. Finally, four important issues on the two-step sequential deposition method will be stated, accompanied with proposed solutions.