Screening Mixed-Metal SnM(III)ChX Chalcohalides for Photovoltaic Applications
arXiv:2306.17745 · doi:10.1021/acs.chemmater.3c01629
Abstract
Quaternary mixed-metal chalcohalides (SnBChX) are emerging as promising lead-free perovskite-inspired photovoltaic absorbers. Motivated by recent developments of a first SnBChX-based device, we used density functional theory to identify lead-free SnBChX materials that are structurally and energetically stable within Cmcm, Cmc2 and P2/c space groups and have a band gap in the range of 0.7 to 2.0 eV to cover out- and indoor photovoltaic applications. A total of 27 SnBChX materials were studied, including Sb, Bi, In for B-site, S, Se, Te for Ch-site and Cl, Br, I for X-site. We identified 12 materials with a direct band gap that meet our requirements, namely: SnInSBr, SnInSI, SnInSeCl, SnInSeBr, SnInTeBr, SnInTeCl, SnSbSI, SnSbSeCl, SnSbSeI, SnSbTeCl, SnBiSI and SnBiTeCl. A database scan reveals that 9 out of 12 are new compositions. For all 27 materials, P2/c is the thermodynamically preferred structure, followed by Cmc2. In Cmcm and Cmc2 mainly direct gaps occur, whereas mostly indirects in P2/c. To open up the possibility of band gap tuning in the future, we identified 12 promising SnBBChChXX alloys which fulfill our requirements and additional 69 materials by combining direct and indirect band gap compounds.
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