High-Efficiency Thin-Film Cadmium Telluride Photovoltaic Cells: Annual Subcontract Report, 20 January 1995 - 19 January 1996

This annual report covers the second year of a 3-year NREL subcontract with the University of Toledo that is focused on improvements in efficiency for radio frequency (rf)-sputtered CdS/CdTe solar cells. In earlier work supported by NREL, the University of Toledo established the viability of two new deposition methods for CdS/CdTe solar cells by fabricating cells with efficiencies greater than10% at air mass (AM) 1.5 on soda lime glass for 'all-sputtered' cells and also for 'all-laser-deposited' cells. Most of our effort has been placed on radio frequency sputtering (RFS) because it was judged to be more economical and more easily scaled to large-area deposition. However, laser physical vapor deposition (LPVD) has remained our method of choice for the deposition of CdCl2 layers andalso for the exploration of new materials such as the ternary alloys including CdSxTe1-x and dopants such as Cu in ZnTe.