Large Area Chemical Bath Deposition of CdS on Cu(InGa)Se2

Abstract

AbstractChemical bath deposition (CBD) is a commonly used method of depositing cadmium sulfide (CdS) films for photovoltaic application. The method is based on decomposition of a sulfur source in an alkaline solution of a cadmium source on the surface of the Cu(In,Ga)Se2 (CIGS) substrate. On the lab scale the CdS film is deposited by submerging a 1” square CIGS substrate in a heated beaker containing the chemical bath. This batch processing method is the one used for record-performing devices. There is an ongoing effort at the National Renewable Energy Laboratory to scale-up the CBD process to deposit CdS films on 6” square substrate. Efforts are focused at designing both batch and flow reactors for depositing uniform, device quality CdS films on larger substrates. Batch reactor designs involve reproducing the deposition process in the beaker on a bigger scale with minimal chemical waste, while flow reactors are designed for continuous processing, such as encountered in roll-to-roll manufacturing lines.