An antibonding valence band maximum enables defect-tolerant and stable GeSe photovoltaics

• DOI: 10.1038/s41467-021-20955-5
• Publication Date: 2021-01-28T11:12:46Z
• Authors: Shun-Chang Liu; Chen-Min Dai; Yimeng Min; Yi Hou; Andrew H. Proppe; Ying Zhou; Chao Chen; Shiyou Chen; Jiang Tang; Ding-Jiang Xue; Edward H. Sargent; Jin-Song Hu
• Keywords: Antibonding molecular orbital; Passivation

Abstract In lead–halide perovskites, antibonding states at the valence band maximum (VBM)—the result of Pb 6 s -I 5 p coupling—enable defect-tolerant properties; however, questions surrounding stability, and a reliance on lead, remain challenges for perovskite solar cells. Here, we report that binary GeSe has perovskite-like VBM arising from Ge 4 -Se coupling; it exhibits similarly shallow bulk defects combined with high stability. We find deep defect density in is ~10 12 cm −3 . devise therefore surface passivation strategy, resulting cells achieve certified power conversion efficiency 5.2%, 3.7 times higher than best previously-reported photovoltaics. Unencapsulated devices show no loss after months storage ambient conditions; 1100 hours under point tracking; total ultraviolet irradiation dosage 15 kWh m −2 ; 60 thermal cycles −40 to 85 °C.