Organic-Inorganic Hybrid Perovskite Films With Enhanced Micro-structure and Photoelectric Properties via Intermittent Annealing Method

An intermittent annealing (IA) method for the preparation of pinhole-free highly uniform and well-crystallized perovskite films was developed. The morphology, structure, optical, and electrical properties of perovskite films treated by the traditional annealing (TA) method and the intermittent annealing method were compared. All of the films were prepared by one-step spin-coating method with ethyl acetate as an anti-solvent under ambient conditions. The effects of the annealing methods on perovskite films were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy and photoluminescence (PL) spectroscopy. Films treated by the traditional annealing method tend to exhibit weak ultraviolet-visible absorption, while the intermittent annealing method was beneficial for preparing highly uniform perovskite films with larger grain size. The method was applicable to MAPbI₃ and Br-doped perovskite materials. The best device treated by the intermittent method in ambient condition shows an power conversion efficiency of 11.5% under simulated AM 1.5 irradiation, which is a 30% enhancement in comparison with that of 8.9% for the device treated by the traditional annealing method.