ILGAR-ZnO as window extension layer in chalcopyrite solar cells

摘要

The concept of a Window Extension Layer (WEL) in chalcopyrite based thin film solar devices is realized by the ILGAR (Ion Layer Gas Reaction) thin layer technology. WEL means the replacement of the conventional buffer layer by a layer of the same material as the window, i.e. an adjacent part of the window is deposited directly onto the absorber by a mild process. The sequential chemical ILGAR method recently extended to metal oxides is applied for the deposition of ZnO layers on Cu(In,Ga)(S,Se){sub}2 absorbers. The process conditions such as temperature, precursor concentration and layer thickness are optimized with respect to the cell performance. The products are characterized in particular by I(V) measurements. With these ZnO WELs obtained by the low cost ILGAR technology at only 155°C process temperature total area efficiencies of 10.8% (best cell on the device) and 10.6% (reproducible average of the three best cells out of eight) are achieved. Corresponding reference devices with CBD-CdS buffers result in 11.4% (best cell).