Efficient quasi-2D tin perovskite solar cells based on mixed monoammonium and diammonium terminal molecules

Tin perovskite is emerging as the most promising candidate for lead-free perovskite solar cells. However, the poor carrier transport properties, such as a short diffusion length, low carrier mobility and severe recombination, limit the boom of tin perovskite solar cells. In this work, we explored mixed monoammonium and diammonium terminal ligands to construct a quasi-2D tin perovskite film. The use of a diammonium ligand reduces the total number of terminal ligands in the film, and it retards perovskite film growth, which enhances the film orientation. These improvements enhance the carrier mobility and carrier diffusion length. As a result, the device shows enhanced current density and power conversion efficiency of 14.3%. The use of a diammonium ligand, p-Xylylenediammonium thiocyanate, enhances the carrier transfer and improves device efficiency.