Intriguing optoelectronic properties of 2D Ca2ZrSe4 chalcogenide perovskite from first principles

Chalcogenide perovskites (CPs) have been attracting great attention as a promising light absorber for the next-generation perovskite solar cells (PSCs), but a deep insight into their material properties is not yet provided. In this work, we report a first-principles study of optoelectronic properties of two-dimensional (2D) CP Ca2ZrSe4 using the GW method combined with the Bethe–Salpeter equation and the Boltzmann transport equation methods. Our calculations demonstrate that one-layer (1L) Ca2ZrSe4 has a direct bandgap of 1.96 eV, light carrier effective masses, and large light absorption coefficients over 105 cm−1 for the visible light region. Furthermore, we find a relatively high electron/hole mobility of 432/64 cm2 V−1 s−1 and a high spectroscopically limited maximum efficiency of 34.4% at room temperature, highlighting the potential of 1L Ca2ZrSe4 as a promising light absorber for PSCs.