Efficient and stable Sn based perovskite solar cells by the modulation of crystallization with bulky organic cation for large nucleation cluster

Organic-inorganic hybrid halide perovskite have been attracting much attention as promising photovoltaic materials owing to their exceptional photovoltaic characteristics. However, even though the rise of progress for the perovskite solar cell was increased, it was still remained the concern for the toxicity of lead in hybrid organolead based perovskite solar cell, which is the harmful materials to the environmental system.Herein, we incorpoarted the homopiperazium (HP2+) into the FASnI3 perovskite to prepare a high-quality perovskite film with a lower defect density. Since the HP is the largest organic cation, that can not enter 3D perovskite but it played a significant role in modulating the crystallinity, morphology and optoelectronic properties of FASnI3 perovskite. When the HPI2 introduced the perovskite precursor solution, it affects the nucleation of perovskite solution by the formation of large pre-nulceation cluster through the linked colloids. It decrease the energy barrier, resulting in a high-quality perovskite film with a lower defect density. Highly oriented perovskite film exhibits the PCE up to a high at 6.88%, with high long-term stability as well which is much higher than that of the pristine FASnI3 perovskite film (4.71%).