Stabilizing buried interface by bilateral bond strength equilibrium strategy toward efficient perovskite photovoltaics

The NiO_x/perovskite interface in p-i-n inverted perovskite solar cells (PSCs) suffers from trap-assisted nonradiative recombination, chemical reactions and weak adhesion. The self-assembled molecules are usually designed to address the above issues. However, absonant bilateral bond strength with NiO_x and perovskite hinders the realization of efficient and stable PSCs. Herein, a bilateral bond strength equilibrium strategy is proposed to stabilize the buried interface in inverted PSCs through functional group and spatial conformation engineering. 1-(benzothiaxole-2-ylthio)succnic acid (BTSA) is adsorbed on the surface of NiO_x through the S atom, π-ring, and N atom in the benzothiazole, making benzothiazole ring parallel to the NiO_x surface, which is beneficial for passivating bilateral defects and improving hole transport. This strategy leads to effective interfacial defect passivation, interfacial chemical reaction suppression and ameliorated electrical properties of NiO_x films, enabling 1.53 eV PSCs and large-area module (764 cm²) with a PCE of 26.98% (certified 26.65%) and 21.98%, respectively.