Spin–orbit coupling effect on electronic, linear and nonlinear optical properties of Bi2S3 and the ternary bismuth sulfide Bi2S2.75Se0.25: Ab-initio calculations

Abstract

Although the relevant properties of the bismuthinite 𝐵𝑖 2 𝑆 3 , it was recently approved that the substitution of Se atoms in the 𝐵𝑖 2 𝑆 3 lattice can significantly enhance its electro-optical properties.In the present work, a detailed study on the structural, electronic and optical properties of 𝐵𝑖 2 𝑆 2.75 𝑆𝑒 0.25 has been carried out based on first principle calculations. The simultaneous effect of Se-doping and spin-orbit coupling (SOC) on bismuth sulfide 𝐵𝑖 2 𝑆 3 was investigated. Our calculations show that 𝐵𝑖 2 𝑆 2.75 𝑆𝑒 0.25 exhibits a narrow direct band gap of 1.062 eV after inclusion of the (SOC). The calculation of the carrier effective masses indicates that 𝐵𝑖 2 𝑆 2.75 𝑆𝑒 0.25 may possess a high electron mobility material which is in accordance with experimental studies. The linear absorption optical spectra for both 𝐵𝑖 2 𝑆 3 and 𝐵𝑖 2 𝑆 2.75 𝑆𝑒 0.25 show that doping bismuthinite with (Se) increases the optical absorption coefficient in the visible range and takes a value up to 10 10 5 𝑐𝑚 −1 . In addition, the dielectric function, optical conductivity and the energy loss function of 𝐵𝑖 2 𝑆 3 and 𝐵𝑖 2 𝑆 2.75 𝑆𝑒 0.25 were also derived. The addition of the (Se) content induces a red shift in agreement with experimental studies. A noticeable effect of the (SOC) on the linear optical parameters was observed. The stability of the excitons was also studied by the estimation of the binding energy value. The dispersion energy parameters of 𝐵𝑖 2 𝑆 3 and 𝐵𝑖 2 𝑆 2.75 𝑆𝑒 0.25 were estimated using a single oscillator model. Some nonlinearities have been computed with and without inclusion of (SOC) showing that 𝐵𝑖 2 𝑆 2.75 𝑆𝑒 0.25 with large nonlinear optical parameters is promising candidate in photonic switching applications.

Prospects of copper–bismuth chalcogenide absorbers for photovoltaics and photoelectrocatalysis

“…35 While for Bi 2 S 3 , the VBM and CBM are derived from Bi s with S p states and Bi p with S p states, respectively. 36,37 Interestingly, in CBS, which contains contributions from both Cu and Bi, its VBM results from the coupling of the Cu d and S p states and its CBM is characterized by Bi p and S p states. 15,25 According to the density of states (DOS) of CBS, as shown in Fig.…”

Broad -band nonlinear optical response in Bi2Te0.6S2.4 alloys based on alloy engineering

“…Alloy engineering holds great promise in thermoelectric devices and have attracted widespread attention in recent years. 34 However, these alloyed Bi 2 S 3 materials either improve their electrical properties or increase the response band of their photodetector, 35 while the nonlinear optics (NLO) response, especially saturable absorption and carrier relaxation in the infrared band, has not been explored so far.…”

Mini‐Review: Progress on the Controllable Synthesis of Micro/Nanoscale Bi2S3 Functional Materials

“…[18][19][20] In these above advanced areas, the manipulation of micro/nanostructured Bi 2 S 3 is of great significance, on account of their high surface energy and reactivity, rich surface sites, and high surface/volume ratio than those of conventional powders. [21,22] For the nanocrystallization of Bi 2 S 3 material, it shows an apparent blue shift on the optical band edge as well as the nonlinear optical response. [23][24][25][26][27][28] Hence, the deep research on Bi 2 S 3 micro/nanomaterials has attracted intensive interests.…”