Enhance the performance of CsPbBr₃ perovskite solar cells with RbBF₄ additive

Abstract All inorganic CsPbBr 3 material exhibits significant application prospects in the field of optoelectronic devices due to its excellent thermal and chemical stability, low fabrication cost, and viability to be fabricated in the ambient atmosphere. Water is a preferred environment friendly solvent for depositing the CsPbBr 3 films. However, CsPbBr 3 perovskite solar cells fabricated using water as solvent usually demonstrate inferior power conversion efficiency compared with the commonly used methanol solvent, which mainly originates from the imperfect morphology and large defect density of the CsPbBr 3 film when water is used as solvent. Herein, a feasible method to improve the film quality of CsPbBr 3 film is proposed through addition of proper amount of RbBF 4 (0.75 mg ml −1 ) into the CsBr/H 2 O solution. The resulting CsPbBr 3 film exhibits compact film morphology, enhanced crystallinity, and less defect density compared with the reference CsPbBr 3 film. As a result, power conversion efficiency is boosted from 6.51% for the reference CsPbBr 3 perovskite solar cell to 8.17% for the target CsPbBr 3 perovskite solar cell.