Ab initio Investigation of quasi-one-dimensional ternary chalcogenides Sr2ZnX3 (X = S, Se, Te) for efficient photovoltaic and thermoelectric applications

The quest for sustainable and renewable energy sources has become a vital global mission. Transition metal chalcogenide materials have garnered significant attention due to their unique low-dimensional physical properties. In this work, we explore the impact of ionic radius in modulating the physical properties of ternary chalcogenides by calculating structural, electronic, optical, and thermoelectric properties of Sr2ZnX3 (X = S, Se, Te) materials using first-principles density functional theory (DFT) as implemented in the WIEN2k program. To evaluate the effect of ionic radius, two novel semiconductors Sr2ZnSe3 and Sr2ZnTe3, were constructed using similar isostructural material Sr(2)ZnS3(.) Further optimized structure reveals that the corner-sharing ZnX4 tetrahedra extended along the b-axis confirms the quasi-one-dimensional (Q1D) nature of Sr2ZnX3 materials. Band structure analysis revealed a wide direct bandgap nature with the values of Sr2ZnS3 (3.4 eV), Sr2ZnSe3 (2.8 eV) and Sr2ZnTe3 (1.75 eV), respectively. The lower effective mass of electrons and holes suggests higher carrier mobility and charge recombination rates, vital for photovoltaic applications. The optical properties of the materials are studied in the energy range of 0-10 eV (IR-Vis-UV region). We found that Sr2ZnTe3 material exhibits higher values of dielectric function, absorption coefficient (alpha approximate to 10(6) cm(-1)), refractive index, and lower reflectivity, which indicates its suitability for photovoltaic application. Thermoelectric properties are crucial for assessing material utility in thermoelectric applications, and the study revealed substantial values of the Seebeck coefficient, electrical conductivity, figure of merit (ZT) greater than 2, power factor, and lower electronic thermal conductivity. The studied properties signify Sr2ZnX3 materials as potential candidates for light-emitting semiconductors and thermoelectric applications.