Plate-let nanostructures for harvesting sunlight

Copper Indium Gallium Diselenide (CIGS) thin films were prepared by one-step electro-deposition technique from a salt bath coupled with thiocyanate complex electrolytes followed by heat treatment in argon gas under atmospheric conditions at 300 degree Celsius. The influences of deposition reduction potentials as well as the CIGS concentrations on the structure, morphology, composition and the optical properties were performed. A reproducible CIGS precursor layer deposition with consistent composition control was demonstrated. The as-deposited films exhibit an amorphous behavior; however, the films displayed good crystallization after heat treatment. The films show very uniform and dense grain formation with platelet- like nanostructures. The optical properties of the films were modified due to heat treatment. The electrical conductivity measurements demonstrated that the transport mechanisms were influenced by three different temperature regions. However, the heat treated films displayed downturn in conductivity at low temperature indicating that there may be trapping at localized sites or scattering of the free carriers, which may be attributed to the over growth and defect sites. The electro-deposition technique demonstrates promise of growing high-quality CIGS thin films for solar cell applications.