Insight into the spin-polarized structural, optoelectronic, magnetic, thermodynamic, and thermoelectric properties of PdBO₂ (B = Al, Cr, and Rh) Delafossite semiconductor

In this work, we performed first-principles calculations based on density functional theory and the semi-classical Boltzmann method to investigate the structural, optoelectronic, magnetic, thermodynamic and thermoelectric properties of PdAlO₂, PdCrO₂ and PdRhO₂ in the Tetragonal phase. Our calculations have revealed that these three compounds have indirect band gaps in the range of 2.14 to 2.68 eV. The thermodynamic properties are investigated using the quasi-harmonic model, where heat capacities at constant pressure and volume, entropy, Debye temperature, and thermal expansion coefficient are analyzed and discussed under both pressure and temperature effects. As a result of this study, PdAlO₂, PdCrO₂, and PdRhO₂ are promising materials for optoelectronic devices, especially photovoltaic materials in solar cells. In doing so, we computed for each compound the Seebeck coefficient, electrical conductivity, electronic thermal conductivity, and figure of merit in the temperature range from 300 to 500 K. The relaxation time and lattice thermal conductivity are calculated as well. Our results reveal that low thermal conductivity and a high Seebeck coefficient can be achieved at the same time. In addition, they exhibit a higher Seebeck for PdAlO₂ compared to PdBO₂ (B = Cr and Rh) up to 1.6 mV/K for PdAlO₂ at 300 K. Thereby improving their thermoelectric performance which makes them attractive thermoelectric materials at high temperatures.