Heavy pnictogen chalcohalides: the synthesis, structure and properties of these rediscovered semiconductors

Abstract

Heavy pnictogen chalcohalides offer various shades from the same palette, like “Paysage” by Nicolas de Staël. Their versatility and tunability lead to a new world of possible applications.

Alternative Lone‐Pair ns2‐Cation‐Based Semiconductors beyond Lead Halide Perovskites for Optoelectronic Applications

“…Each cation is fivefold coordinated by two halide anions and three chalcogen anions, forming edge‐sharing parallel [X(A 2 M 2 )X] rods and, consequently, a chain‐like structure along the a axis ( Figure a). [ 254 ] The halogen interchain coupling remains strong even within the chain structure. Such as in BiSI, the shortest interchain I–I distance is 4.01 Å, slightly shorter than the intrachain I–I distance, which is 4.17 Å.…”

“…Reproduced with permission. [ 254 ] Copyright 2018, Royal Society of Chemistry. c) Histogram of bandgaps and carrier effective masses at the HSE + SOC level for BiSeCl, BiSeBr, BiSeI, and Bi 3 Se 4 Br, respectively.…”

“…Thus, by mapping a series of materials, including PbX (X = S, Se, Te), Sb 2 Te 3 , Bi 2 X 3 (X = Se, Te), and inorganic halide perovskites, into a 2D space with the ES and ET as two coordinates, they found MVB had well‐defined borders to covalent, and iono‐covalent regions, indicating its distinction. [ 229–307 ] Such a map demonstrated that the MVB mechanism approximately possessed one shared electron and moderate electron transfer between adjacent atoms. This predictive model can also give rise to the favorable characteristics in above materials, including large Born effective charge, high optical dielectric constants, strong optical interband transition, etc.…”

Metal Chalcohalides: Next Generation Photovoltaic Materials?

“…Several recent review and perspective articles have highlighted the relevance of some of these materials for photovoltaics and related applications. [10][11][12][13][14] Nevertheless, these are almost exclusively DOI: 10.1002/solr.202100829 Metal chalcohalides have recently been highlighted as so-far overlooked semiconductors that could play an important role in the future of photovoltaics (PV). Indeed, the blooming field of emergent PV technologies is still in search for stable, efficient, and environmentally-friendly light-harvesting materials to be used either in single-junction solar cells or multijunction devices in combination with silicon or another absorbers.…”

“…Several recent review and perspective articles have highlighted the relevance of some of these materials for photovoltaics and related applications. [ 10–14 ] Nevertheless, these are almost exclusively focused on pnictogen chalcohalides, which are of obvious relevance (see Section 3) but not the only existing candidates. In this section, we will survey some of the most relevant metal chalcohalide materials for photovoltaics with a focus (though not exclusively) on low‐toxicity and earth‐abundant elements.…”