Preparation of CsPbBr3 Perovskite Solar Cells Using a Green Solvent

An increasing number of researchers are interested in studying CsPbBr3 perovskite solar cells (PSCs) due to their high stability. However, the use of methanol during the spin-coating process is extremely hazardous, both to humans and the environment. CsBr is very soluble in water, but owing to its high specific heat capacity, water causes uneven crystallization and the creation of pores, which negatively impact the performance of CsPbBr3 devices. In this paper, water is introduced as the solvent for CsBr in place of methanol to prepare CsPbBr3 films and ethanol is used as the surface treatment solvent. The morphology and crystal quality of CsPbBr3 films are improved by varying the concentration and spin-coating cycles of the CsBr/H2O solution and adding ethanol post-treatment. The results show that high-quality CsPbBr3 films with reduced grain boundaries and high phase-purity were obtained by spin-coating 100 mg/mL CsBr/H2O solution three times and using ethanol as a post-treatment. The CsPbBr3 solar cells yielded a maximum efficiency of 7.65% and demonstrate long-term stability over 1100 h.