Enhanced Performance and Stability of Carbon Counter Electrode-Based MAPbI3 Perovskite Solar Cells with p‑Methylphenylamine Iodate Additives

Methylammonium lead iodide perovskite (MAPbI3) demonstrates the disadvantage of poor long-term stability. Additive engineering is an effective measure to address this issue. We have successfully used an organic molecule called p-methylbenzoammonium iodate (p-MePMAI) as an additive to a perovskite precursor. Results showed that p-MePMAI is an excellent additive with functional groups of benzyl and ammonium ions that can improve the performance and stability of carbon counter electrode (CE)-based MAPbI3 perovskite solar cells. Benzene rings and ammonium ion functional groups of p-MePMAI can electrostatically interact with MAPbI3 when a proper amount of p-MePMAI is added. Moreover, the conjugated structure of the benzene ring can effectively reduce the number of trap states in the perovskite film and significantly inhibit nonradiative recombination, further promoting charge transport. The photoelectric conversion efficiency (PCE) of our prepared carbon CE-based MAPbI3 perovskite solar cells increases from 12.76 to 14.54% with the optimization of p-MePMAI. Notably, the device optimized using p-MePMAI additives maintains 85% of the initial PCE after 500 h.