π-Conjugated aromatic amino molecule for interfacial modification in high-performance perovskite solar cells

Aromatic amino cations can effectively inhibit non-radiative recombination caused by defects to improve the stability and efficiency of perovskite solar cells (PSCs), and the pi-conjugated benzene ring of aromatic amino exhibit better conductance compared with alkyl ammonium salts. Further optimization of such molecules requires consideration of their stability, defect passivation performance, and energy level matching between the perovskite and the transport layer. In this work, a novel pi-conjugated aromatic amino molecule naphthylethyl ammonium iodide (NEAI) was applied to the interfacial modification in PSCs. Combining the density functional theory (DFT) calculations and experimental study, it can be revealed that the introduction of NEAI can not only realize the optimization of perovskite layer/HTL interface through defect passivation and more matched energy level, but also improve the moisture stability via the better hydrophobicity of modified films. Finally, the devices achieved a remarkable efficiency of 23.98 % and improved stability, retaining 90 % of the initial efficiency after 600 h placed in the dry room.