Highly Efficient and Stable Perovskite Solar Cells Using an Effective Chelate-Assisted Defect Passivation Strategy.

Due to the sensitivity of the perovskite solar cells to the subtle changes under the ambient atmosphere conditions, many problems have aroused great attention such as collapse of the perovskite structure and efficiency quickly drops . Among them, internal defect also is a big obstacle for high-quality poly-crystalline perovskites, at present it is still difficult to control the density of the trapping sites. Herein, we use a bidentate chelating agent, thenoyltrifluoroacetone (ttfa), to effectively controls the crystallization kinetics, grain sizes and crystal defect of Cs/MA/FA perovskite materials by a nucleation and growth process of perovskite crystals. Realization of crystalline-state-tuning during crystallization process obtain better quality perovskite thin film, with no additional operation that suit the needs of modern industrial production and management, therefore this is an industry produce oriented method . The chelating agent can effectively passivate the defects in perovskite films, leading to a low defect density and a long charge carrier lifetime. As a result, the ttfa-passivated perovskite solar cell demonstrates a high PCE of 19.70% with superior stability retaining over 64% of the initial PCE after two weeks unencapsulated storage in an adverse atmosphere with about 50% relative humidity.