Main-Group Halide Semiconductors Derived from Perovskite: Distinguishing Chemical, Structural, and Electronic Aspects

Abstract

Main-group halide perovskites have generated much excitement of late because of their remarkable optoelectronic properties, ease of preparation, and abundant constituent elements, but these curious and promising materials differ in important respects from traditional semiconductors. The distinguishing chemical, structural, and electronic features of these materials present the key to understanding the origins of the optoelectronic performance of the well-studied hybrid organic-inorganic lead halides and provide a starting point for the design and preparation of new functional materials. Here we review and discuss these distinguishing features, among them a defect-tolerant electronic structure, proximal lattice instabilities, labile defect migration, and, in the case of hybrid perovskites, disordered molecular cations. Additionally, we discuss the preparation and characterization of some alternatives to the lead halide perovskites, including lead-free bismuth halides and hybrid materials with optically and electronically active organic constituents.

Fully‐Inorganic Trihalide Perovskite Nanocrystals: A New Research Frontier of Optoelectronic Materials

“…Since the electronic structure calculations are essential to understand with atomistic detail the optoelectronic properties of nanomaterials, [117,118] more efforts should be focused on the theoretical studies related to fully-inorganic perovskites NCs.…”

Bismuth and antimony-based oxyhalides and chalcohalides as potential optoelectronic materials

“…5,6 The prototypical material, CH3NH3PbI3 is exceptional in having an extremely large dielectric constant on the border of ferroelectricity, suitable band gap for solar absorber application and low hole and electron effective masses. [7][8][9][10][11][12][13][14] The physical mechanisms underlying these optoelectronic halide materials, are not yet fully established, but can at least in part be attributed to the unique chemistry of the ns 2 lone-pair state. Factors that have been discussed include formation of defects with lower charge states, high dielectric constants, and shallow defect levels among others.…”

“…Factors that have been discussed include formation of defects with lower charge states, high dielectric constants, and shallow defect levels among others. [7][8][9][10][11][12][13][14][15] Assessment can be made experimentally using time resolved experiments for carrier lifetimes. 14 In these compounds the cation-s state moves down in energy (forming the lonepair state), separating from the cation-p states (due to the Mass-Darwin effect), so that there is substantial charge transfer only from the cation-p to anion-p states, rather than the cation-s to anion-p states.…”

Automated microfluidic screening of ligand interactions during the synthesis of cesium lead bromide nanocrystals

“…5,10 This has been driven by their exceptional properties, including high photoluminescence quantum yields (PLQYs, routinely >95%), widely tuneable optical characteristics and facile solution-processibility, 11,12 along with the general advantages of metal halide perovskites that include strong optical absorption, high charge-carrier mobilities and extremely high defect tolerance. 13 Given humanity's drastic need to increase sustainable and clean energy, much hope has been pinned on LHP nanocrystals in yielding nextgeneration photovoltaics and electroluminescent diodes. 5,10,14 The propensity of organic-inorganic hybrid LHPs to degrade over time has shifted interest to more stable all-inorganic analogues, in particular CsPbX 3 (X = halide).…”