Thermoelectric performance enhancement of copper iodide pellets through potassium iodide doping

The search for efficient and eco-friendly thermoelectric materials has garnered significant attention to meeting energy demands and address waste heat recovery challenges. Copper iodide (CuI), a p-type semiconductor with non-toxic properties, shows promise for thermoelectric applications, although it has not been extensively studied. This study investigates the thermoelectric performance of CuI doped with varying concentrations (0–9 %) of potassium iodide (KI). This doping significantly modified the electrical and thermal properties of CuI pellets. The electrical conductivity exhibited a notable increase, peaking at 5.08 S m⁻¹ at 373 K with 9 % KI doping, which can be attributed to enhanced charge carrier density and bandgap reduction. The thermal conductivity also increased due to improved electron mobility, whereas the Seebeck coefficient reached a maximum of 7.3 mV K⁻¹ at 7 % KI doping, demonstrating optimal thermoelectric performance at this concentration. The figure of merit (ZT) was maximized at 7 % KI doping, recording a remarkable increase from 0.035 × 10⁻³ (undoped) to 26.95 × 10⁻³ at 373 K. These findings underscore the potential of KI-doped CuI as an efficient thermoelectric material and pave the way for further optimization in advanced energy applications.