Sputtered, oxygenated CdS window layers for higher current in CdS/CdTe thin film solar cells

Abstract

The efficiency of manufactured CdS/CdTe photovoltaic modules can be greatly improved through better collection of available current from the solar spectrum. Typically, only light absorbed in the CdTe absorber layer is collected by the device and light absorption in other layers is lost. A major loss occurs in the CdS window layer, which is strongly absorbing for photon energies above 2.4 ev. RF sputter deposition of CdS in the presence of oxygen has been shown to increase transmission in this spectral region, leading to higher device current. In this work films were examined for transmission and stability upon heating to process temperatures. Numerous devices were made from oxygenated CdS films which showed increased quantum efficiency at wavelengths below 500 nm.