Effect of Side-Group-Regulated Dipolar Passivating Molecules on CsPbBr₃ Perovskite Solar Cells

Abstract

Interfacial passivation of defective perovskite films with a dipole molecule shows a great potential for high-efficiency perovskite solar cells (PSCs). Herein, by regulating the side group of an aniline-based molecule with an electron-withdrawing nitryl (−NO2) or electron-donating methoxyl (−OCH3), the binding energy between −NH2 and under-coordinated Pb2+ in the CsPbBr3 lattice is reinforced, and the dipole-moment-induced surface energy level reconstruction allows for efficient hole extraction for the −OCH3-tailored molecule because of the changed intramolecular electron distribution, whereas −NO2 displays the opposite effect. Finally, the all-inorganic CsPbBr3 PSC achieves a power conversion efficiency (PCE) of 9.81% with an open-circuit voltage (Voc) of 1.632 V and an excellent stability in both high humidity and light irradiation. Upon doping Sm3+ into CsPbBr3, the PCE and Voc are further increased to 10.75% and 1.675 V. This work confirms the importance of a side group on an interface dipole molecule to maximize the charge scavenging, especially for Voc improvement.