Two-dimensional materials for boosting the performance of perovskite solar cells: Fundamentals, materials and devices

As one of the most promising next-generation photovoltaic technologies, organic-inorganic halide perovskite solar cells (PSCs) have undergone great progress during the past decade. To further improve the device performance of PSCs, a series of two dimensional (2D) materials have been introduced into the cell structure with remarkable effects. In this review, recent progress on the applications of 2D materials (i.e., graphene and its derivatives, transitional metal dichalcogenides, other emerging 2D materials and 2D perovskite materials) as electrodes, charge transport layers and additives in perovskite layers in PSCs are summarized. The effect of various 2D materials on charge transport characteristics, crystallization dynamics and long-term stability of PSCs are discussed. Finally, challenges and prospects for the future development of 2D materials-based PSCs are addressed.