G0W0+BSE study of Optoelectronic and Thermoelectric Characteristics of Bulk and Monolayer PdS2 in Orthorhombic Structure for Solar Cell Applications

Abstract

Transition metal dichalcogenides (TMDs) have produced enormous interests due to their novel physical properties and wide ranges of potential applications. This study uses highly accurate first principles calculations within HSE06 functional, G0W0+BSE and Boltzmann transport theory to investigate the optoelectronic and thermoelectric properties of PdS2 in bulk and monolayer phase. PdS2 in orthorhombic structure phase is taken in this paper. PdS2, a Transition metal dichalcogenide (TMDC) compound, has tunable bandgap, rendering it a promising candidate for optoelectronic applications such as solar cells, LEDs, and photodetectors. The lattice parameters obtained with inclusion of van der Waals corrections (vdW-DFC09x) are extremely well matched with experimental results. G0W0 approximation is utilized to accurately estimate the electronic band gap, and the predicted indirect band gap of 0.76 and 1.75 eV in bulk and monolayer shows that PdS2 is semiconductor material and these values are in good agreement with the results obtained experimentally. The optical properties have been studied with inclusion of electron-hole (G0W0+BSE). Optical spectra data shows that PdS2 possesses substantial optical absorption within visible light wavelengths indicating its potential for solar cell applications. The study also examines the thermoelectric properties of the material under investigation in bulk and monolayer such as the electrical and thermal conductivity, Seebeck coefficient, and figure of merit (ZT). The figure of merit ZT value of the bulk phase was found to be 0.9986 while for the monolayer phase, the figure of merit is 1.0067. This study effectively shows an improvement of the figure of merit values by reducing the dimension from bulk to monolayer.