A comparative spin orbit coupling DFT study of opto-electronic properties of Bi2Se3 and Bi2Te3 bulk crystal

Bi2Se3 2 Se 3 and Bi2Te3 2 Te 3 are the ideal candidate for spintronics and many other novel applications due to their strong opto-electronic properties. These materials are regarded as topological insulator as they portray band inversion which is considered to be a key signature of topology. Moreover, because of their superior opto-electronic qualities, Bi2Se3 2 Se 3 and Bi2Te3 2 Te 3 are intriguing in the realm of optical and electronic applications. This paper compares the optical and electronic characteristics of Bi2Te3 2 Te 3 and Bi2Se3 2 Se 3 in the framework of density functional theory taking PBE-GGA and mBJ-GGA as exchange correlation potential. The analysis of band structure and density of states (DOS) confirms the gapped nature without and with SOC calculation. The introduction of SOC gives the accurate result which matches with the experimental figure. Optical properties including reflectivity, absorption coefficient, energy loss function, refractive index, extinction coefficient, and optical conductivity are analyzed without and with SOC. We have also calculated birefringence, dichroism, and the optical skin depth which has not been reported yet for those compounds. The spectroscopic limited maximum efficiency (SLME), which theoretically determines the power conversion efficiency (PCE) of solar cells is also calculated. Based on the optical and electronic properties, possible uses of Bi2Se3 2 Se 3 and Bi2Te3 2 Te 3 are discussed without and with SOC effect.