Controlled growth of textured perovskite films towards high performance solar cells

Abstract

Antisolvent precipitation method has been one of the favored strategies to fabricate compact, smooth and uniform perovskite films for high efficiency solar cells due to its dramatically accelerated crystallization process. However, the excessively fast crystallization restricted the further improvement of the photovoltaic performance. In this work, we introduced CH3NH3Cl into the pristine CH3NH3PbI3 precursor for antisolvent precipitation at low temperature and fabricated high quality perovskite films with desired morphology, crystallinity and optical properties. The X-ray diffractometry and ultraviolent-visible spectroscopy provided ample evidence that CH3NH3Cl exerted significant impacts on the perovskite crystallization process by controlling the delivery speed of PbI2 from the intermediate phase CH3NH3PbI2Cl. The possible reactions in the perovskite formation process were first elaborated. The resultant solar cells demonstrated an average power conversion efficiency around 16.63% and a best efficiency at 17.22% under the standard light illumination condition. In addition, the ion migration was first detected in the perovskite solar cells by an ordinary impedance measurement.