Method of manufacture of sodium doped CIGS/CIGSS absorber layers for high efficiency photovoltaic devices
First Claim
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1. A method of processing a thin film absorber material with enhanced photovoltaic efficiency comprising:
- providing a soda lime glass substrate having a front surface;
forming a barrier layer over the front surface, the barrier layer preventing diffusion of sodium ions from the soda lime glass substrate;
forming an electrode which includes molybdenum over the barrier layer;
depositing a first mixture of a copper species, gallium species, and sodium species to form a first thickness of a first precursor material over the electrode;
depositing a second mixture of a copper species and a gallium species to form a second thickness of a second precursor material over the first precursor material;
depositing an indium species to form a third thickness of a third precursor material over the second precursor material, to thereby form a stack structure of the first thickness, the second thickness, and the third thickness;
subjecting the soda lime glass substrate and the stack structure to a thermal treatment in the presence of H2Se and nitrogen at a temperature above about 400°
C. to form an absorber material from interdiffusion of the copper species, the gallium species, the indium species, and the first sodium species; and
while doing so transferring a sodium species from a back surface of a soda lime glass substrate.
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Abstract
A method for processing a thin-film absorber material with enhanced photovoltaic efficiency includes forming a barrier layer on a soda lime glass substrate followed by formation of a stack structure of precursor layers. The method further includes subjecting the soda-lime glass substrate with the stack structure to a thermal treatment process with at least H2Se gas species at a temperature above 400° C. to cause formation of an absorber material. By positioning the substrates close together, during the process sodium from an adjoining substrate in the furnace also is incorporated into the absorber layer.
264 Citations
17 Claims
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1. A method of processing a thin film absorber material with enhanced photovoltaic efficiency comprising:
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providing a soda lime glass substrate having a front surface; forming a barrier layer over the front surface, the barrier layer preventing diffusion of sodium ions from the soda lime glass substrate; forming an electrode which includes molybdenum over the barrier layer; depositing a first mixture of a copper species, gallium species, and sodium species to form a first thickness of a first precursor material over the electrode; depositing a second mixture of a copper species and a gallium species to form a second thickness of a second precursor material over the first precursor material; depositing an indium species to form a third thickness of a third precursor material over the second precursor material, to thereby form a stack structure of the first thickness, the second thickness, and the third thickness; subjecting the soda lime glass substrate and the stack structure to a thermal treatment in the presence of H2Se and nitrogen at a temperature above about 400°
C. to form an absorber material from interdiffusion of the copper species, the gallium species, the indium species, and the first sodium species; andwhile doing so transferring a sodium species from a back surface of a soda lime glass substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of incorporating sodium species into thin-film photovoltaic absorber for enhancing solar energy conversion efficiency, the method comprising:
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providing a first soda lime glass substrate having a front surface region and a back surface region; forming a bottom electrode material over the front surface region; forming a stack of precursor materials including copper, indium, gallium, and sodium, over the electrode material at a first temperature range; disposing the first soda lime glass substrate having the stack in a furnace containing H2Se gas and nitrogen gas; disposing at least a second soda lime glass substrate next to the first soda lime glass substrate; and heating the first soda lime glass substrate and the second soda lime glass substrate to a second temperature range to cause the precursor materials to react with selenium from the H2Se gas to form a photovoltaic absorber having sodium from both the precursor materials and from the adjoining second soda lime glass substrate. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification