Cu(In,Ga)Se2 thin film solar cells with buffer layer alternative to CdS

Progress in fabricating Cu(In,Ga)Se2 (CIGS) solar cells with ZnS(O,OH) buffer layers prepared by chemical bath deposition (CBD) is discussed in this paper. Such buffer layers could potentially replace CdS in the CIGS solar cell. Total-area conversion efficiency of up to 18.6% has been reported previously using ZnS(O,OH) prepared by CBD. The reported 100 nm CBD ZnS(O,OH) layer was prepared by at least three consecutive depositions, which would make it a relatively expensive replacement for CdS. The recent development of a ZnS(O,OH) layer that enabled to obtain highefficiency devices using a single-layer CBD is reported in this paper. A 14.4%-efficient device is obtained by using onelayer CBD ZnS(O,OH) on commercial-grade Shell Solar Cu(In,Ga)(S,Se)2 (CIGSS) absorber and an up to 17.4% device is obtained by using two-layer CBD ZnS(O,OH) on an NREL CIGS absorber. 2004 Elsevier Ltd. All rights reserved.