Theoretical investigation of the electronic structure and anisotropic optical properties of quasi-1D Sb 2 Se 3 photovolt
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Theoretical investigation of the electronic structure and anisotropic optical properties of quasi‑1D Sb2Se3 photovoltaic absorber materials Xuebing Peng1 · Yangfang Liao1 · Jing Xie1 · Xiaoshu Song1 Received: 19 July 2020 / Accepted: 23 September 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Sb2Se3 is a nontoxic, environmentally friendly photovoltaic absorber material with both a narrow bandgap and high absorption coefficient. The optical properties of Sb2Se3 crystals are theoretically studied herein using first-principles methods. The crystal structure, electronic structure, dielectric function, and absorption coefficient are calculated. The results show that the quasi-one-dimensional structure of Sb2Se3 has an indirect bandgap with a value of 0.953 eV. The bottom of the conduction band and the top of the valence band are mainly formed by Sb 5p and Se 4p hybridized orbitals. For light incident along the [100], [010], and [001] directions, the real and imaginary parts of the dielectric function exhibit clearly anisotropic characteristics. The absorption coefficient is greater than 105 cm−1. Keywords Sb2Se3 · Quasi-one-dimensional · Electronic structures · Anisotropic optical properties · Photovoltaic absorber
1 Introduction The Sb2Se3 crystal is an A2B3 binary material. Due to its excellent characteristics such as lack of toxicity [1–4], environmental friendliness [5], and good carrier mobility (about 10 cm2/V s) [6], this compound has been widely studied by many researchers [7–9]. It is particularly important to note the narrow bandgap [10] and high absorption coefficient (> 105 cm−1) [11] of the Sb2Se3 crystal, which make it very popular for application in the field of solar cells [12, 13]. According to recent research, the best theoretical value of the power conversion efficiency for S b2Se3 solar cells can reach 23.8% [14]. Atomistic calculations have shown that, among V2–VI3 compounds, Sb2Se3 has potential for use in solar cells [15]. Grain boundaries parallel to the ribbons are essentially benign for the recombination of charge carriers [16] due to the special quasi-one-dimensional (quasi-1D) linear structure [17, 18] of the Sb2Se3 crystal. The variation of anisotropic crystals along different directions means that their physical and chemical properties also differ [19–21]. Anisotropy in an absorber material thus plays a very important role in determining the optical properties of * Xiaoshu Song [email protected] 1
School of Physics and Electronic Science, Guizhou Normal University, Guiyang 550001, China
crystals, having considerable research value. A large number of researchers have calculated the electronic structure and optical properties of Sb2Se3 crystals [17, 22, 23]. The thermoelectric properties of S b2Se3 from the bulk to the monolayer structure under high pressure were calculated [24]. The results showed that the lattice constant decreases with increasing pressure, while the bandgap between the bulk and the monolayer also decreases with increa
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