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

ABSTRACT: In lead-halide perovskites, antibonding states at the valence band maximum (VBM)-the result of Pb 6s-I 5p 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 a perovskite-like antibonding VBM arising from Ge 4s-Se 4p coupling; and that it exhibits similarly shallow bulk defects combined with high stability. We find that the deep defect density in bulk GeSe is ~10¹²?cm^-3. We devise therefore a surface passivation strategy, and find that the resulting GeSe solar cells achieve a certified power conversion efficiency of 5.2%, 3.7 times higher than the best previously-reported GeSe photovoltaics. Unencapsulated devices show no efficiency loss after 12 months of storage in ambient conditions; 1100?hours under maximum power point tracking; a total ultraviolet irradiation dosage of 15 kWh m^-2; and 60 thermal cycles from -40 to 85?°C.

SUBMITTER: Liu SC 

PROVIDER: S-EPMC7844217 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature