Research progress of wide bandgap perovskite materials and solar cells

Organic-inorganic metal halide perovskites are a new type of photovoltaic material, they have attracted wide attention and made excellent progress in recent years. The power conversion efficiency of a single-junction perovskite solar cell has been increased to 25.2% just within a decade. Meanwhile, crystalline silicon solar cells account for nearly 90% of industrialized solar cells and have a maximum efficiency of 26.7%, approaching to their theoretical limit. It is more difficult to further improve the efficiency of single junction solar cells. It has been shown that multi-junction tandem solar cells prepared by stacking absorption layers with different bandgaps can better use sunlight, which is one of the most promising strategies to break the efficiency limitation of single-junction solar cells. Due to the bandgap tunability and low-temperature solution processability, perovskites stand out among many other materials for manufacturing multi-junction tandem solar cells. Wide bandgap perovskites with a bandgap of 1.63 eV or above have been combined with narrow band gap inorganic absorption layers such as silicon, copper indium gallium selenide, cadmium telluride or narrow bandgap perovskite to produce high efficiency tandem solar cells. In addition to the promoting of the efficiency improvement of solar cells, the wide bandgap perovskites have broad applications in photovoltaic building integration and photocatalytic fields. Therefore, it is very important to explore and develop high quality wide bandgap perovskite materials and solar cells. Unfortunately, the wide bandgap perovskites have several intrinsic weaknesses, including being more vulnerable to the migration of halogen ions under being illuminated, more defects, and greater possibility of energy level mismatching with the charge transport layers than the narrow bandgap counterparts, which limits the further development of the wide bandgap perovskite solar cells. In this review, the development status of wide bandgap perovskite solar cells is summarized and corresponding strategies for improving their performance are put forward. Furthermore, some personal views on the future development of wide bandgap perovskite solar cells are also presented here in this paper.