Huang, Y.T.; Kavanagh, S.R.; Righetto, M.; Rusu, M.; Levine, I.; Unold, T.; Zelewski, S.J.; Sneyd, A.J.; Zhang, K.; Dai, L.; Britton, A.J.; Ye, J.; Julin, J.; Napari, M.; Zhang, Z.; Xiao, J.; Laitinen, M.; Torrente-Murciano, L.; Stranks, S.D.; Rao, A.; Herz, L.M.; Scanlon, D.O.; Walsh, A.; Hoye, R.L.Z.: NaBiS2 as a Next-Generation Photovoltaic Absorber. In: 2024 IEEE 52nd Photovoltaic Specialist Conference (PVSC), Seattle, WA, USA : 9-14 June 2024Piscataway, NJ: IEEE, 2024. - ISBN 978-1-6654-6426-0, p. 422-424
10.1109/pvsc57443.2024.10749179
Open Access Version
Abstract:
I−V−VI2 ternary chalcogenides were gaining more attention recently owing to their high air stability along with earth-abundant and nontoxic compounds. More interestingly, some of them have been predicted to be potential “perovskite-inspired materials” that can exhibit defect tolerance. In this work, we investigated the optoelectronic properties of cation-disordered NaBiS2 nanocrystals, which have a steep absorption onset, with absorption coefficients >105 cm−1 just above its pseudo-direct bandgap of 1.4 eVe Surprisingly, an ultrafast photoconductivity decay and long-lived charge-carrier population almost independent of defect densities were simultaneously observed in N aBiS2 nanocrystals. Through the density functional theory calculations, these unusual features are found to be highly associated with the non-bonding S p orbitals above the upper valence band, which can be further enhanced by cation inhomogeneity. Our work hence reveals the critical role of cation disorder on both absorption characteristics and charge-carrier kinetics of I−V−VI2 ternary chalcogenides.