Synergistic Defect Passivation for Highly Efficient and Stable Perovskite Solar Cells Using Sodium Dodecyl Benzene Sulfonate

Polycrystalline perovskite films with a lot of ionic defects and pinholes are the key factors to both the efficiency and stability of organic–inorganic halide perovskite devices. Here, an efficient additive modification process is reported for passivating defects in the perovskite film with sodium dodecyl benzene sulfonate (SDBS), leading to valid defect passivation of perovskite films and conspicuous improvement in both power conversion efficiency (PCE) and stability of mixed-cation perovskite solar cells (PSCs). Upon incorporating SDBS in perovskite precursor, the PCE of planar structure mixed-cation PSCs shows a best PCE of 20.88% with negligible hysteresis behavior (1.27), which are outstanding and better than that of the control PSCs (PCE = 19.15% and H-index = 8.18). The benzene sulfonic acid group of SDBS attracts lead ions of the perovskite and attaches on the surfaces of the perovskite crystal, which obviously slows down the process of perovskite crystallization and benefits from the high-quality film with lower defect density preparation. Also, the long-chain alkyl groups of SDBS with hydrophobicity benefit from the perovskite film with better water stability. In addition, SDBS modification decreases the electron trap density, improving charge utilization, suppressing charge recombination, and resulting in an increase of the efficiency of the mixed-cation PSC devices. Moreover, PSCs with optimal SDBS passivation show a better ambient stability compared with the control PSCs. These results indicate that the synergistic interfacial passivation of SDBS in perovskites is beneficial in fabricating highly efficient and air stable PSCs.