Structural and Optical Properties of Sputtered CdTe Thin Films Deposited on Flexible Substrates for Photovoltaic Applications

초록

Cadmium telluride (CdTe) is a leading candidate for solar cell applications. Two key properties of CdTe are its band gap (1.45 eV) and its high optical absorption coefficient. A thin film of CdTe with thickness of ca. 2 mm will absorb nearly 100% of incident solar radiation.4 Another advantage of CdTe is that several methods are available for deposition including vacuum evaporation, electrodeposition, chemical vapour deposition (CVD) and closed space sublimation (CSS). The highest efficiency (21%) solar cells have been prepared by CSS. Other methods such as physical vapour deposition (PVD), electrodeposition and sputtering have also demonstrated potential to achieve high performance levels. Adam Lee Sanford, RF magnetron triode sputtering of CdTe and ZnTe films and solar cclls, Ph.D thesis, Iowa State University, 2002 CdTe is a leading material for solar cell technology bεcause of its nearly ideal direct bandgap (l .5eV) for absorption of solar energy, and because of the low cost and adaptability to large-scale manufacturing. [P. Meyers, and S. Albright, Prog. Photovolt. Res. AppL 8, 161-169 (2000).] To date, the highest cell efficiencies reported in the lab are near 16%. Champion module efficiencies of 9.1 % have been realized for commercial production.