Defect-induced enhancements of optical and thermoelectric properties in hydrothermally synthesized Fe-doped ZnO nanostructures

Defect engineering has become a fascinating strategy to improve the performance of thermoelectric materials. This study focuses on enhancing the thermoelectric properties of hydrothermally synthesized iron (Fe)-doped zinc oxide (ZnO) nanoparticles, with varying Fe concentrations, while investigating their structural and photoluminescence characteristics. X-ray diffraction (XRD) confirmed the hexagonal wurtzite crystal structure with a preferential orientation along the (101) plane, irrespective of doping levels. Scanning electron microscopy (SEM) revealed a nanorod-like morphology that improved progressively with Fe doping. Energy-dispersive X-ray spectroscopy (EDX) entailed qualitative and quantitative analysis of key elements, including Zn, O and Fe, confirming the successful incorporation of the dopant. Photoluminescence (PL) spectroscopy demonstrated a near-band-edge (NBE) UV emission redshift from 381.86[Formula: see text]nm to 383.11[Formula: see text]nm, along with a shift in the green band (GB) emission from 506[Formula: see text]nm to 526[Formula: see text]nm, indicative of Fe dopant substitution into the ZnO lattice. The incorporation of Fe significantly enhanced the electrical conductivity and Seebeck coefficient, achieving a peak value of 108[Formula: see text]S/cm and [Formula: see text]V/K, respectively at 900[Formula: see text]K. This enhancement is attributed to the introduction of lattice defects, specifically oxygen and zinc vacancies, which contribute to increased scattering phenomena. These results emphasize the potential of Fe-doped ZnO as a promising material for thermoelectric applications and possibly provide a feasible approach to incorporate the role of defects in the design of modern thermoelectric materials.