Effect of Processing Technique Factors on Structure and Photophysical Properties of Perovskite Absorption Layer by Using Two-Step Spin-Coating Method

The investigation of crystal growth is crucial for us to improve the film quality and photophysical properties of CH3NH3PbI3(MAPbI(3)). In the two-step spin-coating process, the crystal structure could be modulated by controlling the growth conditions of PbI(2)and CH3NH3I (MAI) layers. In this paper, the PbI(2)layer was treated with annealing under different times. A liquid-liquid diffusion (LLD) mechanism is proposed to modify the deposition of MAI precursor solution and enhance the flatness of organic-inorganic hybrid perovskite film. Furthermore, the perovskite films are prepared using different concentrations of MAI. The evolution process of perovskite structure is observed by modulating the concentration of MAI. The spin-coating of moderate MAI tends to form high quality MAPbI(3)films with enhanced absorption and carrier extraction capabilities. The high concentration of MAI would cause the perovskite phase transition, which provides a novel perspective to modulate the structure of organic-inorganic hybrid perovskite in the two-step spin-coating process, although it deteriorates the device performance.