BACK CONTACT LAYER STRUCTURE FOR GROUP IBIIIAVIA PHOTOVOLTAIC CELLS
First Claim
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1. A method of manufacturing a Cu(In,Ga)Se2 thin-film solar cell on a conductive substrate, comprising:
- forming a multilayer back contact on a conductive flexible substrate, wherein the multilayer back contact includes a diffusion barrier layer;
forming an intermediate layer on the diffusion barrier layer, wherein the intermediate layer is a metal layer;
forming an absorber precursor including Cu species, In species, Ga species and Se species over the intermediate layer;
applying heat to the absorber precursor to form therefrom an absorber layer including a Cu(In,Ga)Se2 thin film compound, wherein the step of forming the absorber layer causes some of the Se species in the absorber layer to diffuse towards the intermediate layer and at least partially transforms the intermediate layer into a metal-selenide layer and wherein the diffusion barrier layer inhibits diffusion of the Se species across the diffusion barrier during the step of applying heat;
disposing a transparent conductive layer on the thin film absorber layer, the transparent layer including a buffer layer deposited on the thin film absorber and a transparent conductive oxide layer formed on the buffer layer; and
forming a top terminal on the transparent conductive layer, thereby resulting in the Cu(In,Ga)Se2 thin-film solar cell.
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Abstract
Described are new ohmic contact materials and diffusion barriers for Group IBIIIAVIA based solar cell structures, which eliminate two way diffusion while preserving the efficient ohmic contacts between the substrate and the absorber layers.
7 Citations
14 Claims
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1. A method of manufacturing a Cu(In,Ga)Se2 thin-film solar cell on a conductive substrate, comprising:
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forming a multilayer back contact on a conductive flexible substrate, wherein the multilayer back contact includes a diffusion barrier layer; forming an intermediate layer on the diffusion barrier layer, wherein the intermediate layer is a metal layer; forming an absorber precursor including Cu species, In species, Ga species and Se species over the intermediate layer; applying heat to the absorber precursor to form therefrom an absorber layer including a Cu(In,Ga)Se2 thin film compound, wherein the step of forming the absorber layer causes some of the Se species in the absorber layer to diffuse towards the intermediate layer and at least partially transforms the intermediate layer into a metal-selenide layer and wherein the diffusion barrier layer inhibits diffusion of the Se species across the diffusion barrier during the step of applying heat; disposing a transparent conductive layer on the thin film absorber layer, the transparent layer including a buffer layer deposited on the thin film absorber and a transparent conductive oxide layer formed on the buffer layer; and forming a top terminal on the transparent conductive layer, thereby resulting in the Cu(In,Ga)Se2 thin-film solar cell. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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1-1. A solar cell, comprising:
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a flexible conductive substrate; a back contact formed on the flexible conductive substrate, wherein the back contact includes a contact layer formed on the flexible conductive substrate and a diffusion barrier layer formed on the contact layer; an ohmic contact layer is formed on the diffusion barrier layer of the back contact, wherein the ohmic contact layer is a metal-selenide layer; a thin film absorber layer including Cu species, In species, Ga species and Se species formed on the ohmic contact layer; a transparent layer deposited on the thin film absorber layer, the transparent layer including a buffer layer deposited on the thin film absorber and a transparent conductive oxide layer formed on the buffer layer; and a top terminal formed on the transparent layer; wherein the diffusion barrier layer inhibits diffusion of the selenium species from the thin film absorber layer across the diffusion barrier layer.
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Specification