The effect of Cu doping on the thermoelectric properties of Cs2CuxAg1-xBiBr6 perovskites

Abstract

This study focuses on examining the thermoelectric properties of Cs2CuxAg1-xBiBr6 perovskites and investigates the influence of lattice thermal conductivity on their thermoelectric performance. To achieve this, the study utilizes a combination of first-principles calculations and Boltzmann transport theory. The calculated structural properties, obtained through the generalized Perdew-Burke-Ernzerhof approximation (GGA-PBE), closely align with both experimental and theoretical data for lattice constants and bulk modulus. The electronic properties were assessed using the TB-mBJ (Tran-Blaha-modified Becke-Johnson) method, indicating relatively small band gaps within the range of 1.146 eV for Cs2CuBiBr6 and 2.072 eV for Cs2AgBiBr6. The materials exhibit significant Seebeck coefficients and controllable lattice thermal conductivity between 0.067 and 0.662 W/mK at room temperature, with the relaxation time being determined using the Drude model. The study revealed that the most significant zT values, approximately 0.80, were observed when x = 0.5 in the Cs2CuxAg1-xBiBr6 perovskite material. This indicates that these perovskites possess the ability to efficiently and inexpensively convert heat into electrical energy. Consequently, these findings propose the potential of Cs2CuxAg1-xBiBr6 perovskites as a favorable option for real-world thermoelectric applications. The study further highlights the importance of utilizing lattice thermal conductivity to enhance the overall thermoelectric performance of such materials.