Davis, Joseph & Negley

Midwest Research Institute

James C Keane

Raghu Nath Bhattacharya

Rommel Noufi

Kannan Ramanathan

Miguel A Contreras

John R Tuttle

Falah S Hasoon

Andrew L Tennant

Holm Wiesner

Sarah E Asher

Kannan V Ramanathan

James Dolan

A process for making a thin film ZnO/Cu(InGa)Sesolar cell without depositing a buffer layer and by Zn doping from a vapor phase, comprising: depositing Cu(InGa)Selayer on a metal back contact deposited on a glass substrate; heating the Cu(InGa)Selayer on the metal back contact on the glass substrate to a temperature range between about 100&#xb0; C. to about 250&#xb0; C.; subjecting the heated layer of Cu(InGa)Seto an evaporant species from a Zn compound; and sputter depositing ZnO on the Zn compound evaporant species treated layer of Cu(InGa)Se.

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The present invention provides an economical, simple, dry and controllable semiconductor layer junction forming process to make cadmium free high efficiency photovoltaic cells having a first layer comprised primarily of copper indium diselenide having a thin doped copper indium diselenide n-type region, generated by thermal diffusion with a group II(b) element such as zinc, and a halide, such as chlorine, and a second layer comprised of a conventional zinc oxide bilayer. A photovoltaic device according the present invention includes a first thin film layer of semiconductor material formed primarily from copper indium diselenide. Doping of the copper indium diselenide with zinc chloride is accomplished using either a zinc chloride solution or a solid zinc chloride material. Thermal diffusion of zinc chloride into the copper indium diselenide upper region creates the thin n-type copper indium diselenide surface. A second thin film layer of semiconductor material comprising zinc oxide is then applied in two layers. The first layer comprises a thin layer of high resistivity zinc oxide. The second relatively thick layer of zinc oxide is doped to exhibit low resistivity.

Cadmium-free junction fabrication process for CuInSe.sub.2 thin film

A photovoltaic cell exhibiting an overall conversion efficiency of 13.6% is prepared from a copper-indium-gallium-diselenide precursor thin film. The film is fabricated by first simultaneously electrodepositing copper, indium, gallium, and selenium onto a glass/molybdenum substrate (12/14). The electrodeposition voltage is a high frequency AC voltage superimposed upon a DC voltage to improve the morphology and growth rate of the film. The electrodeposition is followed by physical vapor deposition to adjust the final stoichiometry of the thin film to approximately Cu(In.sub.1-n Ga.sub.x)Se.sub.2, with the ratio of Ga/(In+Ga) being approximately 0.39.

Preparation of copper-indium-gallium-diselenide precursor films by

High quality thin films of copper-indium-gallium-diselenide useful in the production of solar cells are prepared by electrodepositing at least one of the constituent metals onto a glass/Mo substrate, followed by physical vapor deposition of copper and selenium or indium and selenium to adjust the final stoichiometry of the thin film to approximately Cu(In,Ga)Se.sub.2. Using an AC voltage of 1-100 KHz in combination with a DC voltage for electrodeposition improves the morphology and growth rate of the deposited thin film. An electrodeposition solution comprising at least in part an organic solvent may be used in conjunction with an increased cathodic potential to increase the gallium content of the electrodeposited thin film.

Preparation of copper indium gallium diselenide films for solar cells

Preparation of cuxinygazsen (X=0-2, Y=0-2, Z=0-2, N=0-3) precursor films

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Lakewood, CO, United States of America

James C Keane