Defect-Controlled Copper Iodide: A Promising and Ecofriendly Thermoelectric Material

Earth-abundant and non-toxic materials are important in the utilization of thermoelectric technology. Here, the thermoelectric behavior of copper iodide (CuI), which is prepared in bulk using a simple synthetic approach, is reported. The as-prepared CuI has a high Seebeck coefficient of approximate to 431 mu VK-1 with a resistivity approximate to 0.26 Omega cm(-1), resulting in a room temperature thermoelectric power factor of approximate to 70 mu Wm(-1)K(-2). The thermoelectric properties are tuned by changing the defect chemistry via thermal annealing. Annealing at moderate temperatures (approximate to 400 K) improves thermoelectric power factor, from its room temperature value of approximate to 142 mu Wm(-1)K(-2) to approximate to 160 mu Wm(-1)K(-2) at 353 K. Detailed analysis reveals that this is caused by iodine depletion upon annealing, which compensates for the intrinsic defects present in the form of copper vacancies that are responsible for the p-type conductivity of the CuI.