High-quality CH3NH3PbI3 thin film fabricated via intramolecular exchange for efficient planar heterojunction perovskite solar cells

Abstract

The high-quality CH3NH3PbI3 perovskite thin film with excellent coverage and uniformity was prepared using an intramolecular exchange technology via a low-temperature, two-step sequential deposition process. The PbI2(DMSO) complex was synthesized at room temperature without any additives and was deposited, then the CH3NH3I solution was deposited subsequently. The further controllable thermal annealing process resulted in the complete formation of flat and uniform CH3NH3PbI3 thin film with large-size grains and (110) preferred crystallographic orientation. The perovskite solar cells (PSCs) with a very simple inverted planar heterojunction structure of ITO/PEDOT:PSS/CH3NH3PbI3/PCBM/Al and without other buffer layers, e.g., C60, LiF, BCP, etc., were fabricated, resulting in a power conversion efficiency (PCE) as high as 14.26%. The results suggest that the low-temperature, two-step sequential deposition process with intramolecular exchange technology provides a good route to fabricate high-quality perovskite thin film and efficient PSCs, which would match with large-scale, high-output roll-to-roll (R2R) printing/coating techniques.