Band-Edge Orbital Engineering of Perovskite Semiconductors for Optoelectronic Applications

Abstract

Lead (Pb) halide perovskites have achieved great success in recent years due to their excellent optoelectronic properties, which is largely attributed to the lone-pair s orbital-derived antibonding states at the valence band edge. Guided by the key band-edge orbital character, a series of ns 2containing (i.e., Sn 2+ , Sb 3+ , Bi 3+ ) Pb-free perovskite alternatives have been explored as potential photovoltaic candidates. On the other hand, based on the band-edge orbital components (i.e., M 2+ s and p/Xp orbitals), a series of strategies have been proposed to optimize their optoelectronic properties by modifying the atomic orbitals and orbital interactions. Therefore, understanding the band-edge electronic features from the recently reported halide perovskites is essential for future material design and device optimization. Here, this Perspective first attempts to establish the bandedge orbital-property relationship using a chemically intuitive approach, and then rationalizes their superior properties and understands the trends in electronic properties. We hope that this Perspective will provide atomic-level guidance and insights toward the rational design of perovskite semiconductors with outstanding optoelectronic properties.

Linear Relationship between the Dielectric Constant and Band Gap in Low-Dimensional Mixed-Halide Perovskites

“…This can be attributed to the band gap relying on the atomic structure (bond length, bond angle, and so on). As mentioned earlier, the change in the bond angle can be ignored, and increasing d lowers the bond strength by decreasing the orbital overlap interaction, which usually leads to a larger E g , 58 as the band gap is only related to Pb−X bond length in the CsPbX 3 system. Therefore, in mixed-halide perovskite materials in different dimensions, as the halogen changes from Cl to Br to I, the bond length of Pb−X increases, which increases the dielectric constant and decreases the band gap.…”

Structure–Composition–Property Relationships in Antiperovskite Nitrides: Guiding a Rational Alloy Design

“…For conventional ABX 3 perovskites, it is well known that the B-site cation and X-site anion have major impacts on the electronic structures, while the A-site cation does not contribute to the band edge because of its highly ionic nature. , However, the effect of composition on the electronic properties in antiperovskites has not been fully understood . Here, we take six antiperovskite nitrides X 3 NA (X 2+ = Mg 2+ , Ca 2+ , Sr 2+ ; A 3– = P 3– , As 3– , Sb 3– , Bi 3– ) as examples to study their composition–property relationship.…”

Ultrafast Speed, Dark Current Suppression, and Self-Powered Enhancement in TiO2-Based Ultraviolet Photodetectors by Organic Layers and Ag Nanowires Regulation

“…Photodetectors (PDs), including photomultipliers, photoresistors, and photodiodes, can convert optical signals to electrical signals. − Ultraviolet (UV) light, spanning the wavelength range from 10 to 400 nm, is the major cause of human skin cancer and skin aging. Therefore, UV PDs are attracting increasing interest, and efforts are focused on materials selection and structure design. − …”