Controllable Crystal Film Growth via Appropriate Substrate-Preheating Treatment for Perovskite Solar Cells Using Mixed Lead Sources

We employed mixed PbCl2:PbAc2 as lead sources and followed the two-step sequential deposition method to prepare the perovskite films. We focused on the influence of substrate-preheating treatment on crystal growth, morphology, optical and electrical properties of the final perovskite film, as well as the device performance. A combination of characterizations including scanning electron microscope (SEM), conducting atomic force microscopy (C-AFM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), UV–vis absorption, time-resolved photoluminescence spectra (TRPL), and surface photovoltage spectroscopy (SPS) was utilized to investigate the effect of substrate-preheating treatment. It was demonstrated that appropriate substrate-preheating treatment could realize controllable perovskite crystallization, leading to high-quality perovskite film with improved optical and electrical properties. The devices with the optimized perovskite films exhibited good reproducibility and stability, delivering an ideal PCE of 15.37%, with decent FF of 73.84%, high Voc of 0.98 V, and Jsc of 21.24 mA/cm2.