Synergistic resonant molecular passivator of various defects for high-performance perovskite solar cells

The defects and mismatched energy-level at interfaces of perovskite solar cells (PSCs) can weaken their performance and stability. In this paper, we introduce 3,8-dibromo-1,10-phenanthroline-5,6-dione (BPO) into PSCs to align perovskite energy levels and passivate defects. The theoretical and experimental results indicate that BPO molecules with zwitterionic resonance structure can accept electrons and change the charge state of perovskite surface to modify the energy-level. In addition, the multi-group passivation of BPO molecules, which contain "bipyridyl nitrogen" and bicarbonyl groups, can chelate the Pb defects such as Pb–I antisite (PbI) and iodine vacancy (VI). Notably, the BPO-doped PSCs achieve a power conversion efficiency of 23.18 % with enhanced efficiency retention ratio of 85 % (55 % for control sample) after 1000 h test at 65 % relative humidity. This study provides an effective choice for the exploration of novel additives for device performance improvement.