Effective dopants for CuI single nanocrystals as a promising room temperature thermoelectric material

Abstract Room temperature (RT) thermoelectric (TE) materials are of great importance for harvesting energy from solar heat or other hot environments. The nontoxic, earth-abundant copper iodide (CuI) has a high Seebeck coefficient at RT; however, its electrical conductivity needs to be further enhanced for better TE performance. In this work, pure and doped CuI single nanocrystals were synthesized by the precipitation method in ethanol medium. The formed CuI nanoparticles (NPs) have high crystallinity in the gamma phase. Among several metallic dopants, Tb and Fe were found to be effective for enhancing the TE performance of CuI NPs. The Tb-doped sample was found to have the highest TE power factor. The concentration of this dopant was optimized for maximum TE performance. The TE power factor and Figure of merit values at RT were enhanced from approximately 30 μW/m K2 and 0.01 for the pure CuI NPs to approximately 210 μW/m K2 and 0.08 for the 0.05 mol% Tb-doped sample, respectively. This enhancement is correlated with the incorporation of this dopant in mixed chemical states. The pure and Tb-doped CuI NPs were characterized by several techniques, including XDR, XPS, TEM, SEM, and UV–visible spectroscopy. The Tb-doped sample might be suitable for RT TE devices and generators.