Synergistic Effects of Energy Level Alignment and Trap Passivation via 3,4-Dihydroxyphenethylamine Hydrochloride for Efficient and Air-Stable Perovskite Solar Cells

Grain boundaries and surface defect states in perovskite films damage the charge transport mechanism by acting as nonradiative recombination centers, thus resulting in poor device performance and unsatisfactory long-term stability. For this aim, we added 3,4-dihydroxyphenethylamine hydrochloride (3,4-DpACl) as an effective additive to chlorobenzene antisolvent and used it during perovskite fabrication. The characterization results infer that the 3,4-DpACl material not only assists in forming a smoother perovskite film along with the reduction of residual lead iodide but also brings a passivation effect from the possible chemical interaction between the C═O of 3,4-DpACI molecules and uncoordinated Pb 2+ ions of the perovskite material. In addition, employing the 3,4-DpACl tailors the energy levels of the perovskite layer and reduces mismatch energy between the valence band of the perovskite layer and hole transport layer (HTL). Overall, the 3,4-DpACl-contained antisolvent records a champion efficiency of 21.17% for optimized perovskite solar cells (PSCs). The optimized triple-cation PSCs show a higher stability against humidity and irradiance. They maintain 83% of their original power conversion efficiency (PCE) after 1600 h of exposure to ambient air with a humidity level of 35–40%. Furthermore, after 1056 h of irradiance with simulated sunlight in an ambient air environment, they retain 81.6% of their initial PCE.