Improvement of Colloidal Characteristics in a Precursor Solution by a PbI2‑(DMSO)2 Complex for Efficient Nonstoichiometrically Prepared CsPbI2.8Br0.2 Perovskite Solar Cells
mediaposted on 19.10.2020, 14:12 by Hang Zhao, Xiaolong Liu, Jia Xu, Zhenzhen Li, Yao Fu, Honglu Zhu, Luxin Yan, Zhike Liu, Shengzhong Frank Liu, Jianxi Yao
The optoelectronic properties of all-inorganic perovskite solar cells are greatly affected by the quality characteristics of films, such as the defect concentration, crystal growth orientation, crystallinity, and morphology. In this study, a PbI2-(DMSO)2 complex is adopted to partially replace PbI2 as the lead source in the preparation of perovskite precursor solutions. Due to the rapid dispersion of the PbI2-(DMSO)2 complex in a solvent, raw materials can rapidly react to form perovskite colloids with a narrow size distribution. Such uniform colloidal particles are found to be beneficial for achieving films with improved quality and highly orientated growth along the  direction. The optimized film exhibits a clearly improved crystallinity and a decrease in defect concentration from 4.29 × 1015 cm–3 to 3.20 × 1015 cm–3. The device based on the obtained all-inorganic CsPbI2.8Br0.2 perovskite finally achieves an increase in photovoltaic power conversion efficiency from 10.5 to 14.15%. In addition, the environmental stability of the device also benefits from the improved film quality. After 480 h of storage in air, the device can still maintain nearly 80% of its initial performance.