[18a-G204-1~8] 13.8 Optical properties and light-emitting devices

[18a-G204-2] Assessing the performance of the Tran-Blaha modified Becke-Johnson exchange potential for optical constants of semiconductors in the ultraviolet-visible light region

〇Kousuke Nakano¹, Tomohiro Sakai² (1.AGC Innovative R&D center, 2.AGC Product R&D center)

Keywords:First principle calculation, Optical constant, Materials informatics

Recently, the materials informatics (MI) paradigm, in which novel materials are designed or searched for using techniques of information science and/or computational physics, has attracted much attention because of rapid improvements in computer performance that have allowed the application of such techniques in this context. High-throughput DFT calculations are often performed to create large-scale databases of target physical properties or the explanatory variables (i.e., descriptors) for machine learning or data mining in MI. Therefore, it is important to investigate whether or not DFT calculation can quantitatively predict a target physical property or its explanatory variables before attempting a high-throughput calculation. In this study, we focus on optical constants of semiconductors in the ultraviolet and visible (UV-Vis) light region, namely, the refractive index n and extinction coefficient k, which are fundamental physical properties to be taken into account when designing industrial optical materials such as pigments, optical thin films, and lenses. In DFT, the Tran-Blaha modified Becke-Johnson exchange potential (TB-mBJ) and the random phase approximation (RPA) dielectric function have been widely used for evaluating optical constants of semiconductors. Although it seems to be a promising framework for the high-throughput calculation because of the low calculational cost, there are no theoretical guarantees that the approximate calculation can quantitatively reproduce experimental values of various kinds of compounds. In this presentation, we report on the performance of DFT with TB-mBJ and the RPA dielectric function for optical constants of semiconductors in the UV-Vis light region. We calculate optical band gaps, refractive indices n, and extinction coefficients k of semiconductors listed in the Handbook of Optical Constants of Solids (Academic Press, 1985, 1991, 1998) and compare the results with experimental values. The results show that the calculated band gaps and optical constants agree well with the experimental values for various kinds of compounds.