초록 ▼

An improved efficiency thin film solar cell is disclosed. Nanoscale indentations or protrusions are formed on the cross sectional surface of a carrier layer, onto which a thin metal film is deposited. Additional layers, including semiconductor absorber and collector layers and a window layer, are di

An improved efficiency thin film solar cell is disclosed. Nanoscale indentations or protrusions are formed on the cross sectional surface of a carrier layer, onto which a thin metal film is deposited. Additional layers, including semiconductor absorber and collector layers and a window layer, are disposed on the metal film, thereby completing the solar cell. The nanostructure underlying the metal film serves to reduce the work function of the metal and thereby assists in the absorption of holes created by solar photons. This leads to more efficient electricity generation in the solar cell. In a further embodiment of the present invention the cross sectional surface of the semiconductor absorber layer is also modified by nanoscale indentations or protrusions. These indentations or protrusions have the effect of altering the size of the semiconductor band gap, thereby optimizing the radiation absorption properties of the solar cell.

대표청구항 ▼

1. A thin film solar cell characterized by improved efficiency of electricity generation from solar photons comprising: a. a carrier layer comprising a polymer, wherein a surface of said carrier layer comprises periodically repeating indents and protrusions, each said indent having a depth of 5 nm a

1. A thin film solar cell characterized by improved efficiency of electricity generation from solar photons comprising: a. a carrier layer comprising a polymer, wherein a surface of said carrier layer comprises periodically repeating indents and protrusions, each said indent having a depth of 5 nm and a width of less than approximately 100 nm;b. a metal back contact layer deposited on the periodically repeating indents and protrusions on said carrier layer surface, wherein a surface of said metal contact back layer in contact with said carrier layer surface comprises periodically repeating indents and protrusions located and sized to correspond to said periodically repeating indents and protrusions on said carrier surface layer, said periodically repeating indents and protrusions being configured to reduce work function;c. a p-type semiconductor absorber layer comprising Copper Indium Gallium Diselenide disposed on a surface of said metal back contact layer opposite said metal back contact layer surface with indents, wherein said p-type semiconductor absorber layer includes a band gap;d. an n-type semiconductor collector layer disposed on a surface of said p-type semiconductor absorber layer not in contact with said metal back contact layer to form a p-n junction with a voltage differential;e. a window layer comprising zinc oxide (ZnO) disposed on a surface of said n-type semiconductor collector layer opposite said p-n junction; andf. an electrical contact comprising an aluminum grid positioned on a surface of aid window layer to receive electrons from said n-type semiconductor collector layer. 2. The solar cell of claim 1, wherein said carrier layer comprises a polyimide with a thickness greater than 100 micrometers. 3. The solar cell of claim 1, wherein said metal back contact layer comprises one or a combination of Molybdenum, Copper, Silver, Nickel or other metals with good electrical conductivity and has a thickness equal to 0.5 micrometers. 4. The solar cell of claim 1, wherein said p-type semiconductor absorber layer has a thickness in the range of 2-3 micrometers. 5. The solar cell of claim 1, wherein said n-type semiconductor collector layer comprises Cadmium Sulfide and has a thickness equal to 0.1 micrometers. 6. The solar cell of claim 1, further comprising electrical connectors connected to said metal back contact layer and said electrical contact, whereby an electrical current travels therebetween. 7. The solar cell of claim 1, wherein the surface of said p-type semiconductor absorber layer in contact with said n-type semiconductor collector layer at said p-n junction comprises periodically repeating indents and protrusions, said indents having a depth of 5 nm and a width of less than 100 nm, and wherein the depth and width of said indents is selected so that the band gap in said p-type semiconductor absorber layer has a dimension sized to maximize efficiency of the solar cell. 8. The solar cell of claim 7, wherein the depth and width of said indents in said p-type semiconductor absorber layer is selected to optimize absorption of solar photons by said solar cell. 9. The solar cell of claim 1, where a surface of said solar cell facing the sun comprises periodically repeating intents and protrusions, each indent having a depth of less than 5 nm and a width of 100 nm. 10. A thin film solar cell characterized by improved efficiency of electricity generation from solar photons comprising: a. a carrier layer comprising a polyimide having a thickness greater than 100 μm, wherein a surface of said carrier layer comprises periodically repeating indents and protrusions, each said indent having a depth of 5 nm and a width of less than 100 nm;b. a metal back contact layer deposited on the pattern of indents and protrusions on said carrier layer surface, wherein a surface of said metal contact back layer in contact with said carrier layer has periodically repeating indents and protrusions located and sized to correspond to said periodically repeating indents and protrusions on said carrier surface layer;c. a p-type semiconductor absorber layer comprising Copper Indium Gallium Diselenide having a band gap disposed on a surface of said metal back contact layer opposite said surface of said metal back contact layer in contact with said carrier layer, wherein a surface of said p-type semiconductor absorber layer opposite said metal back contact layer comprises periodically repeating indents and protrusions;d. an n-type semiconductor collector layer disposed on said surface of said p-type semiconductor collector layer with said periodically repeating indents and protrusions to form a p-n junction, wherein said n-type semiconductor collector layer surface is configured to contact said p-type semiconductor absorber layer surface at said p-n junction;e. a window layer comprising zinc oxide (ZnO) disposed on a surface of said n-type semiconductor collector layer opposite said p-n junction; andf. an electrical contact comprising an aluminum grid positioned on a surface of aid window layer to receive electrons from said n-type semiconductor collector layer. 11. The solar cell of claim 10, wherein said metal back contact layer comprises one or a combination of molybdenum, copper, silver, or nickel and has a thickness of 0.5 μm; said p-type semiconductor absorber layer and has a thickness in the range of 2-3 μm; and said n-type semiconductor collector layer comprises cadmium sulfide and has a thickness of 0.1 μm. 12. The solar cell of claim 10, wherein a depth of said indents and a width of said indents in the surface of said p-type semiconductor absorber layer at said p-n junction are selected to optimize size of the band gap in said p-type semiconductor absorber layer, thereby maximizing solar-electric energy conversion.