Systematic first-principles investigation of electronic, optical and thermoelectric properties of all-inorganic layered ruddlesden-popper mixed halide perovskite Cs2SnI2Br2

Report on systematic study of the impact of layer dependent structural properties, electronic structures and optical characteristics on the two-dimensional (2D) Ruddlesden-Popper (RP) perovskite Cs2SnI2Br2 using first principles computation within the density functional theory method including a spin orbit coupling contribution. Our results reveal that the predicted 2D-layered RP perovskite Cs2SnI2Br2 are structurally and energetically stable which can be realized in experiments. It is also shown that the band gap and optical absorption charac-teristics of the 2D-layered RP perovskite Cs2SnI2Br2 are dependent on thickness variation. Interestingly, Cs2SnI2Br2 exhibited an interesting absorption coefficient in the visible region. The transport equations were solved in order to evaluate the effect of the Sn based 2D-layered RP perovskite on thermoelectric performance. It is found that Cs2SnI2Br2 has lower thermal conductivity and higher electrical conductivity for T = 300 K. In addition, Cs2SnI2Br2 is expected to get the highest figure of merit. This result provides an outstanding opportunity for this 2D RP perovskite with potential applications in solar cells and thermoelectric applications.