Rapid Thermal Processing of Back Contacts for Cadmium
Telluride Solar Cells
Timothy Ohno, Joseph Beach, and Colin A. Wolden
Summary: A high-throughput method to produce back contacts for cadmium telluride (CdTe)
solar cells that improves the cell’s properties
Description: Cadmium telluride (CdTe) solar cells on ultra-thin glass substrates are light and
flexible. These traits can enable new applications that require high specific power, unique form
factors, and low manufacturing costs. This invention relates to a simple, high throughput
approach for producing electrical back contacts to CdTe solar cells. In this method, the
deposition and activation steps of a copper-doped zinc telluride back buffer layer (ZnTe:Cu) are
decoupled; the buffer and metallization layers are first deposited by evaporation at low
temperature followed by rapid thermal processing (RTP) to precisely control the activation. The
process is fast (< 1 min.) and offers a significant reduction in thermal budget over conventional
techniques. The technique offers unique tools to control the redistribution of elements within
the back contact, resulting in enhanced device efficiency through improvements in the fill
factor, open circuit voltage, and reproducibility.
Main Advantages of this Invention
 Significant reduction in thermal concerns
 Simple, high yield process
 Can be applied to multiple devise
Potential Areas of Application
 Solar energy
 Thermally sensitive materials
 Small electronics
ID number: 14028
Intel ectual Property Status: US utility patent pending (application 14/706,814)
Publications: J. Li et al. Sol. Energ. Mat. Sol. C., 2015, 133, 208-215. (Available upon request.)
Opportunity: We are seeking an exclusive or non-exclusive licensee for implementation of this
For more information contact:
William Vaughan, Director of Technology Transfer
Colorado School of Mines, 1500 Illinois Street, Guggenheim Hall Suite 314, Golden, CO 80401
Phone: 303-384-2555; e-mail: wvaughan@mines.edu