Here we introduce a new, potentially scalable way of producing hybrid metal halide perovskite (CH3NH3PbI3) layers — a compound with exceptional semiconducting properties and high levels of light absorption, which makes it one of the most promising and actively developing area of photovoltaics.
Our goal was to develop a new approach to obtaining large-size perovskite layers by the conversion of metallic lead in solutions of RPM. To that end, the following objectives were set:
• establish the optimal solvent and the optimal conditions for perovskite synthesis;
• compare treatment with iodine solutions with treatment with iodine vapor;
• determine the most effective encapsulant.
A new technique was proposed based on immersion of lead films and direct conversion of metallic lead by a redox reaction in polyiodide solutions (dip-coating). We determined the optimal conditions for obtaining high-quality perovskite films: toluene was found to be the most suitable solvent and the optimal synthesis time in toluene was determined to be 45 minutes.
In addition, the possibility of substituting iodine solution treatment of perovskite films with iodine vapor treatment was studied, but no particular advantage was found.
To tackle the issue of perovskite degradation, encapsulation trials were conducted. All five studied encapsulates (Kapton, polyurethane, ethylene-vinyl acetate, polyisobutylene, and UV epoxy) were found to be effective against the harmful influence of sunlight and temperature on the quality of the perovskite layer, and only polyurethane and ethylenevinyl acetate proved to protect the perovskite film when immersed in water. It can be concluded that the these two compounds (PU and EVA) improve perovskite’s stability to all external factors and, therefore, are acceptable encapsulants.
Our findings can be used for future development of perovskite solar cells.