Thermoelectric properties, X-ray photoelectron spectroscopy, Raman spectroscopy, and electronic structures have been studied for Mn-substituted CuInSe 2 chalcopyrites. Raman spectroscopy verifies the lattice disorder due to the introduction of Mn into the CuInSe 2 matrix, leading to a slight suppression of thermal conductivity. On the other hand, the Mn substitution significantly increases the electrical conductivity and Seebeck coefficient. Therefore the thermoelectric figure of merit, ZT, has been enhanced by over two orders of magnitude by the introduction of Mn into CuInSe 2 . These materials are p-type degenerate semiconductors, containing divalent Mn species as confirmed by X-ray photoelectron spectroscopy. The crystal structure of Mn-substituted CuInSe 2 , as well as related ternary and quaternary diamond-like semiconductors, can be viewed as a combination of an electrically conducting unit, the

We report solvothermal preparations of nanocrystalline CuIn 1-x Al x Se 2 materials prepared from the reaction of Se, CuX 2 (X = Clor stearate), InCl 3 , and Al(oleate) 3 in refluxing oleylamine for 30 minutes to 3 hours. Scanning electron microscopy (SEM) images reveal morphologies consisting of hexagonal plates (100-400 nm diameter) with smaller isomorphic nodules. Micro-Raman spectroscopy, x-ray diffraction, and optical bandgap data are consistent with Al 3+ incorporation into the chalcopyrite structure. For aluminum-containing reactions, product Al/(In+Al) ratios are estimated to be between 0.15 and 0.35 regardless of the indiumaluminum stoichiometry employed in the reaction. When Se is added to the reaction last, the reaction pathway involves an early-formed Cu 2-x Se(s) intermediate that appears to react with Inand Al-containing species simultaneously. This intermediate is avoided when heating InCl 3 , Al(oleate) 3 , and Se together prior to Cu addition, but the final product includes Se contamination that must be removed or reacted by annealing.