Chemical incorporation of copper into indium selenide thin films

Indium selenide thin-films have been treated in a copper-containing chemical bath with the goal of forming a precursor layer capable of being converted into copper indium diselenide. The conversion process was carried out by annealing the layers in a tube furnace in the presence of selenium vapour. The phase content of the layers as a function of composition and annealing temperature has been investigated by Raman spectroscopy. It is concluded that copper selenide is formed during the chemical bath treatment and that during annealing the copper selenide reacts first with elemental selenium vapour and then with the indium selenide to form chalcopyrite CuInSe2. Secondary phases of CuIn3Se5 and Cu-Au ordered CuInSe2 have been detected in annealed copper-poor layers

Chemical incorporation of copper into indium selenide thin-films for processing of CuInSe2 solar cells

A chemical method of incorporating copper into indium selenide thin-films has been investigated, with the goal of creating a precursor structure for conversion into CuInSe2 layers suitable for solar cell processing. The precursor and converted layers have been investigated with scanning electron microscopy, x-ray diffraction, Raman spectroscopy and x-ray photoelectron spectroscopy. From these measurements, the incorporation of copper into the indium selenide layers is concluded to proceed by an ion-exchange reaction. This reaction results in the formation of a precursor layer with a graded compositional depth-profile containing the crystalline phases In2Se3 and Cu2-xSe. Selenization of the precursor layer homogenises the composition and forms chalcopyrite CuInSe2. These CuInSe2 layers exhibit a dense microstructure with rough surface morphology, which is ascribed to a non-optimal selenization process. Solar cells with the structure ZnO:Al/i-ZnO/CdS/CuInSe2/Mo/Glass have been processed from the selenized layers and have exhibited efficiencies of up to 4% under simulated AM1.5 illumination

Incorporation of copper into indium gallium selenide layers from solution

A chemical method for the incorporation of copper into indium gallium selenide (IGS) layers has been developed. The resulting copper-containing precursor layers have been annealed in the presence of selenium vapour with the goal of forming Cu(In, Ga)Se2 (CIGS) layers. It is found that copper ions in solution are incorporated into IGS layers during immersion, resulting in the formation of a precursor layer containing both copper selenides and IGS. When aqueous solutions are used for this process, corrosion of the molybdenum back contact occurs by reduction of copper ions in the solution. Use of an ethylene glycol solution prevents corrosion of the Mo and allows higher process temperatures, corresponding to higher reaction rates. During annealing, the precursor layers are converted into CIGS and the morphology of these layers is strongly affected by the availability of selenium whilst the substrate temperature is ramped up