Structural, electronic, optical, and thermoelectric studies on Zintl SrCd2Pn2 (Pn=P/As) compounds for solar cell applications: A First Principle Approach

Abstract

Strontium-based Zintl materials SrCd2Pn2 (Pn = P/As) have been investigated here for their thermoelectric applications. The fundamental structural, optoelectronics and transport properties of Zintl SrCd2Pn2 (Pn = P/As) compounds were determined by employing the full potential linearized augmented plane wave approach (FP-LAPW). The formation and dynamical stabilities have been confirmed by formation energy and phonon dispersion studies. The established band structures using the modified Becke–Johnson potential (mBJ) reveals a direct energy bandgap (Eg) of 1.58 eV and 1.15 eV for SrCd2P2 and SrCd2As2, respectively. The DOS spectra disclose Pn(P/As) states are present in the valence band while Sr states are present in the conduction band. The optical features of the compounds were analyzed from dielectric constants, refractive index, extinction coefficient, and energy loss function against photon energy (eV) up to 30 eV. We observed that the material absorption by falling the light is fascinating in the visible region, revealing a viable choice for optoelectronics application. We evaluated transport properties like the Seebeck coefficient, electrical and thermal conductivity, power factor versus temperature, carrier concentration, and chemical potential with the classical Boltzmann transport theory. The computed Seebeck coefficients for SrCd2P2 and SrCd2As2 are found to be equal to 242μVK−1 and 239 μVK−1 at 300 K and 255 μVK−1, 257 μVK−1at 1200 K. The highest values of the power factor obtained at 1200 K are 5.88 × 1011 W/K2m.s, 5.21 × 1011W/K2m.s for SrCd2P2 and SrCd2As2, respectively. The tremendous optoelectronic characteristic and outstanding power factor values predicted this group could be favorable for uses in solar and thermoelectric uses.