Float line deposited transparent conductors - Implications for the PV industry

The flat glass industry successfully commercialized pyrolytically deposited low emissivity glass based on color-suppressed fluorine-doped tin oxide in 1990. The current production capability of this product approaches 500,000 m(2) of coated glass per year. Spin-off products for the photovoltaic (PV) industry were introduced by LOF in 1991 and enjoy considerable success in this emerging technology. Many PV researchers, however, still prefer to produce optimized tin oxide off-line in CVD furnaces as they can be produced on higher performing but higher cost substrates. In this paper, we discuss the characteristics of on-line production of PV transparent conductors (TCO), including the tradeoffs required when a coating process is incorporated onto a neat glass line. We conclude by suggesting that eventual large scale commercialization of thin film photovoltaics dictates the use of on-line TCO based on economics, the excellent uniformity and repeatability, and ready availability. We believe that the PV researchers are best served by understanding the capabilities of on-line tin oxide production, and tailoring their programs towards the characteristics of these new cost effective TCOs.