Enhance the performance of CsPbBr3 perovskite solar cells with RbBF4 additive

All inorganic CsPbBr3 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. For CsPbBr3 based perovskite solar cells (PSCs), water is a preferred environment friendly solvent to deposit the corresponding CsPbBr3 films. However, CsPbBr3 PSCs 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 CsPbBr3 film. Herein, a feasible method to improve the film quality of the CsPbBr3 film is proposed through addition of proper amount of RbBF4 (0.75 mg mL-1) into the CsBr/H2O solution. The resulting CsPbBr3 film exhibits compact film morphology, enhanced crystallinity, and less defect density compared with the reference CsPbBr3 film. As a result, power conversion efficiency is boosted from 6.51% for the reference CsPbBr3 PSC to 8.17% for the target CsPbBr3 PSC.