CuGaTe_2 with a chalcopyrite structure demonstrates promising thermoelectric properties. The maximum figure of merit ZT is 1.4 at 950 K. CuGaTe_2 and related chalcopyrites are a new class of high-efficiency bulk thermoelectric material for high-temperature applications.

Chalcopyrite CuGaTe(2): a high-efficiency bulk thermoelectric material.

https://apo.ansto.gov.au/dspace/bitstream/10238/4396/2/FLORES-JOHNSON_Numerical_Analysis_Of_The_Effect_Of_Weld-Induced_2012_06.pdf

Numerical analysis of the effect of weld-induced residual stress and plastic damage on the ballistic performance of welded steel plate

Photoluminescence (PL) and photoluminescence excitation measurements over a temperature range 12 K<T<300 K on high quality CuGaTe2 crystals grown by the vertical Bridgman method were completed. The whole PL spectrum consists of two regions. The first region includes PL bands E1 at 1.431 eV, E2 at 1.426 eV, and E3 at 1.417 eV, together with their phonon replicas while in the second region we have a PL band D0 at 1.338 eV with its well-resolved LO-phonon replicas (ℏωLO=26.5 meV). All these PL bands appear to be at higher energy than the lowest (fundamental) band gap energy EgA. The possible origin of observed PL bands is discussed.

/pdf/photoluminescence-and-photoluminescence-excitation-study-of-1blscgl77w.pdf

Photoluminescence and photoluminescence excitation study of CuGaTe2

Recent advances in high performance thermoelectric materials have garnered unprecedented attention owing to their capability of direct transformation of heat energy to useful electricity. Copper Telluride (Cu2Te), a member of the chalcogenide family has emerged as a state-of-the-art thermoelectric material with low thermal conductivity and high thermoelectric (TE) performance, however, this material exhibits exceptional transport properties only at very high temperatures. In this study, we have investigated the synergistic effects of Ga doping on the TE performance by first principles calculations along with experimental validations. The DFT (Density Functional Theory) calculations predicted that Ga doping, within considerable limits enhanced the electrical conductivity and Seebeck coefficients in Cu2Te. This proof of concept was validated by experimental synthesis of Ga doped Cu2Te by simple direct annealing for shorter durations of 48 hours at 1120 oC  (~1/4th) than in previous work and subsequent thermoelectric characterization. The enhanced electrical conductivity, thermopower, and moderate thermal conductivities led to the optimized TE performance in 3 atomic % Ga doping (Cu1.97Ga0.03Te), exhibiting a ZT value of 0.46 at 600 K, almost three times that of pristine Cu2Te in this temperature range. This comprehensive study provides the platform for developing new low-cost and energy efficient TE materials with enhanced ZT performance in medium temperature applications.

Synergistic effect of band convergence and carrier transport on enhancing the thermoelectric performance of Ga doped Cu 2 Te at medium temperatures

A method and system to modify a surface composition of thin film Group IBIIIA VIA solar cell absorbers having non-uniformly distributed Group IIIA materials or graded materials, such as Indium (In), gallium (Ga) and aluminum (Al). The graded materials distribution varies between the surface and the bottom of the absorber layer such that a molar ratio of (Ga+Al)/(Ga+Al+In) is the highest at the bottom of the absorber layer and the lowest at the surface of the absorber. Within the bulk of the absorber, the molar ratio gradually changes between the bottom and the surface of the absorber. In one embodiment, the surface composition of a graded absorber layer may be modified by removing a top portion or slice of the absorber layer, where the molar ratio is low so as to expose the inner portions of the absorber layer having a higher molar ratio of graded materials.

M. Sesha Reddy

Papers

Investigations on polycrystalline CuGaTe2 thin films

Structural properties of CuGaTe2 thin films

Electrical properties of CuGaTe2 thin films