Programme

O.11 -- Oral, VCTP-48

Date: Tuesday, 1 August 2023

Time: 16:40 - 17:05

Electronic band structure and thermoelectric properties of bismuth oxychalcogenides

Tran Van Quang (1) and Nguyen Huy Viet (2)

(1) Faculty of Electronics and Telecommunications, VNU University of Engineering and Technology, Hanoi, Viet Nam; (2) Institute of Physics, Vietnam Academy of Science and Technology

Recently, a new class of bismuth oxychalcogenides materials (Bi2O2X, X=S,Se,Te) has attracted a lot of attention due to its potential applications in the fields of (opto-)electronic and thermoelectric devices. First-principles simulations based on density-functional theory (DFT) with standard LDA/GGA approximations of xc-energy not only severely underestimate the bandgap but also lead to a negative bandgap of bismuth oxychacogenides in some cases. Since accurate description of the bandgap is important in determining electronic and thermoelectric properties, advanced functionals should be used to resolve the issue. Recently self-consistently determined onsite U and intersite V interactions have been demonstrated to be effective in dealing with the bandgap problem. In this report, we present the results of calculations using advanced funtionals, namely DFT+U+V and HSE06, and show that the description of excited states of bismuth oxychacogenide can be significantly improved and the semiconducting nature is preserved. Thermoelectric coefficient calculations are also carried out for comparisons between different methods and experiments.

Presenter: Tran Van Quang