This letter describes the fabrication and characteristics of high‐efficiency thin‐film CdS/CdTe heterojunction solar cells. CdS films have been prepared by chemical bath deposition and p‐CdTe films have been deposited by close‐spaced sublimation. A CdS/CdTe solar cell of greater than 1 cm2 area with an AM1.5 efficiency of 15.8% is reported.

Thin‐film CdS/CdTe solar cell with 15.8% efficiency

Cu(In,Ga)Se2 and CdTe heterojunction solar cells grown on rigid (glass) or flexible foil substrates require p-type absorber layers of optimum optoelectronic properties and n-type wide-bandgap partner layers to form the p–n junction. Transparent conducting oxide and specific metal layers are used for front and back electrical contacts. Efficiencies of solar cells depend on various deposition methods as they control the optoelectronic properties of the layers and interfaces. Certain treatments, such as addition of Na in Cu(In,Ga)Se2 and CdCl2 treatment of CdTe have a direct influence on the electronic properties of the absorber layers and efficiency of solar cells. Processes for the development of superstrate and substrate solar cells are reviewed. Copyright © 2004 John Wiley & Sons, Ltd.

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Development of thin‐film Cu(In,Ga)Se2 and CdTe solar cells

Low cost processing of CIGS thin film solar cells

▪ Abstract Polycrystalline thin film solar cells on copper indium diselenide (CulnSe2) and its alloys and cadmium telluride (CdTe) appear to be the most promising candidates for large-scale application of photovoltaic energy conversion because they have shown laboratory-efficiences in excess of 15%. Heterojunction devices with n-type cadmium sulfide (CdS) films show very low minority carrier recombination at the absorber grain boundaries and at the metallurgical interface, which results in high quantum efficiences. Open circuit voltages of these devices are relatively low owing to the recombination in the space charge region in the absorber. Further improvements in efficiency can be achieved by reducing the recombination current, especially in devices based on CulnSe2 and its alloys. Low-cost manufacturing of modules requires better resolution of a number of other technical issues. For modules based on CulnSe2 and its alloys, the role of Na and higher deposition rates on device performance need to be bett...

POLYCRYSTALLINE THIN FILM SOLAR CELLS:Present Status and Future Potential

Polycrystalline thin films of copper indium diselenide and its alloys with gallium and sulphur (CIGS) have proven to be suitable for use as absorbers in high-efficiency solar cells. Record efficiency devices of 20% power conversion efficiency have been produced by co-evaporation of the elements under high vacuum. However, non-vacuum methods for absorber deposition promise significantly lower capital expenditure and reduced materials costs, and have been used to produce devices with efficiencies of up to 14%. Such efficiencies are already high enough for commercial up-scaling to be considered and several companies are now trying to develop products based on non-vacuum deposited CIGS absorbers. This article will review the wide range of non-vacuum techniques that have been used to deposit CIGS thin films, highlighting the state of the art and efforts towards commercialization.

Non‐vacuum methods for formation of Cu(In, Ga)(Se, S)2 thin film photovoltaic absorbers

Low cost methods for the production of semiconductor films for CuInSe2/CdS solar cells☆

Cd‐rich mercury cadmium telluride (MCT) is a promising material for thin‐film solar cell applications. In this letter we present data on the deposition of MCT films by a simple electroplating technique and report on the highest efficiency polycrystalline MCT thin‐film solar cell to date, which has an efficiency of 10.6% under AM1.5 illumination.

Mercury cadmium telluride solar cell with 10. 6% efficiency

A method of fabricating a thin film heterojunction photovoltaic cell which comprises depositing a film of a near intrinsic or n-type semiconductor compound formed of at least one of the metal elements of Class II B of the Periodic Table of Elements and at least tellurium and then heating said film at a temperature between about 250° C. and 500° C. for a time sufficient to convert said film to a suitably low resistivity p-type semiconductor compound. Such film may be deposited initially on the surface of an n-type semiconductor substrate. Alternatively, there may be deposited on the converted film a layer of n-type semiconductor compound different from the film semiconductor compound. The resulting photovoltaic cell exhibits a substantially increased power output over similar cells not subjected to the method of the present invention.

Thin film heterojunction photovoltaic cells and methods of making the same

A stable front contact current collector grid 36 is provided for thin-film photovoltaic devices. The current collector grid 36 is deposited on a textured patterned surface 35 of an optically transparent electrically conductive layer 34 that insures stable bonding between the current collector grid 36 and the transparent conductive layer 34. The photovoltaic device 30 includes a substrate 32; an optically transparent electrically conductive layer 34 having a textured patterned surface 35; a front contact current collector grid 36; a first semiconductor layer 38; a second semiconductor layer 40; and an electrically conductive film 42 in contact with the second semiconductor layer.

Eric S. Tseng

Papers

Low cost methods for the production of semiconductor films for CuInSe2/CdS solar cells☆

Mercury cadmium telluride solar cell with 10. 6% efficiency

Thin film heterojunction photovoltaic cells and methods of making the same

Stable contact between current collector grid and transparent conductive layer

Low cost thin film chalcopyrite solar cells