A Lewis-base-based antisolvent method for fabricating triple-cation perovskite solar cells

Recently, mixed antisolvents have been widely used to fabricate perovskite solar cells. In this study, we prepared a mixed antisolvent by mixing tetrahydrofuran (THF), which is a Lewis base, and ethyl acetate (EA). We found that the addition of THF to the antisolvent decreased the amount of residual PbI2 and charge traps in the triple-cation perovskite owing to crystallization control and defect passivation through Lewis base-acid interactions. In the proposed process, an improved power conversion efficiency (PCE) was achieved when another Lewis base, dimethyl sulfoxide (DMSO), was not used in the perovskite precursor preparation, although most other recent studies mixed DMSO in the precursor solvent. The PCE of the optimum device in the inverted structure based on the triple-cation perovskite fabricated using the THF-EA mixed antisolvent was 19.26%, and that of the device with pure EA was 16.14%. The THF-EA antisolvent also yielded better environmental stability than that using the pure EA antisolvent. The incorporation of tetrahydrofuran into ethyl acetate enhances the power conversion efficiency of the perovskite solar cell, primarily due to an elevation in the short-circuit current.