Interface modification of perovskite solar cell for synergistic effect of surface defect passivation and excited state property enhancement

The efficiency of perovskite solar cell (PSC) is significantly affected by the charge transport and recombination behaviors at the interfaces between the perovskite photoactive layer and charge transport intermediate layers. Especially, the defects, existing in those interfaces, induce non-radiative charge carrier recombination, reducing the stability of the device along with its performance. In this work, we newly design an imidazole- and methoxy-functionalized triphenylamine based hole-transport material (HTM), which has defect-passivating functionality together with proper carrier-transportation property, for the p-i-n PSC devices. Additionally, it is also designed to preserve its enhanced molecular dipole moment at the excited-state with longer lifetime through excited-state intramolecular proton transfer (ESIPT) process, consequently beneficial to improve the Vbi of the device. The designed HTM molecule, having a synergistic effect of defect-passivation and photo-enhanced dipole characteristic, is confirmed to be advantageous to produce PSCs with higher performance and stability.