Tryptaminium Iodide as an Additive of Isopropanol Green Antisolvent for Efficient and Stable Perovskite Solar Cells

In order to overcome the problem of poor quality of perovskite films obtained from alcohol alike green antisolvents, we herein introduce an additive, tryptaminium iodide (TPAI), into an isopropanol (IPA) green antisolvent to fabricate high-quality perovskite films toward efficient and stable perovskite solar cells (PSCs). The interactions between perovskite (methylammonium lead iodide, MAPbI3) and TPAI are systematically and deeply investigated by means of X-ray photoelectron spectroscopy and proton nuclear magnetic resonance. It is found that there exist coordination and hydrogen bonds between TPAI and MAPbI3, which causes preferred orientation growth of perovskite crystals, notable passivation of traps, enhanced carrier extraction, and suppressed charge recombination. Consequently, the green antisolvent additive engineering enhances the power conversion efficiency (PCE) from 17.27 to 20.40%. Furthermore, the PSC prepared through the green antisolvent additive engineering maintains 81% of the initial PCE when stored in the ambient condition for 1000 h, in contrast to 56% for the PSC based on the IPA antisolvent without an additive.