Structural, mechanical, electronic, optical, and thermoelectric analysis of cubic-tetragonal halide perovskites CsGeX3 (X = Cl, Br, I)

In this study, using the first-principles calculation we presented a new field of materials concerning the transparent conducting halide perovskites CsGeX3 (X = Cl, I, Br) in the phases: ideal cubic, S-cubic, D-cubic, and tetragonal. The study aimed to explore and investigate the most mechanical stable state by calculating the elastic constant C-ij. Our findings indicated that the preferential ground state mechanical stability is the non-magnetic state. On analysis of optical properties, we found high optical transmission practically similar to 80%. Electrical conductivity is also high, and the figure of merit is close to similar to 1. Based on the results obtained from theoretical DFT calculation, it is proposed that these materials may be an appropriate candidate for photovoltaic and other optoelectronic device applications. As they have high coefficients, low reflection, and strong optical conductivity at the UV-Vis range which are crucial for designing a transparent conducting material for possible technological applications.