Defect Passivation by Natural Piperine Molecule Enabling for Stable Perovskite Solar Cells with Efficiencies over 23%

Effective modulation of defects and carrier transport behaviors at the surfaces and grain boundaries of solution-processed perovskites has proven to be a vital strategy for suppressing charge recombination, allowing for efficient and stable perovskite solar cells (PSCs). Herein, a natural molecule (E,E)-1-[5-(1,3-benzodioxol-5-yl)-1-oxo-2,4-pentadienyl]-piperidine (BOPP) with a carbonyl group and π-conjugated structure is incorporated into perovskites using a one step antisolvent procedure. The as-prepared perovskites improved crystallization and decreased defect density, which is ascribed to the passivation effect of BOPP due to the carbonyl group forming coordination bonds with undercoordinated Pb2+ ions via Lewis acid-base interactions. Incorporating BOPP into the perovskite layer results in a better arrangement of energy levels between the perovskite and Spiro-OMeTAD interface, contributing to more efficient carrier injection and transport. The results show that the BOPP-passivated device achieves a champion power conversion efficiency (PCE) of 23.37% with a steady-state power output of 22.95%, compared with a PCE of 21.49% for the pristine device. At the same time, the unencapsulated devices maintained around 95% of their original PCEs after aging under relative humidities of 15%-30% over 3000 h. Moreover, this work gives a viable avenue to fabricate high-quality perovskite layers for optoelectronic applications using natural compound additives.