8% efficient CuInS2 solar cells by electrochemically removed Cu–S Phases

Abstract Investigations on how to replace the toxic KCN etching for the removal of Cu–S phases during the preparation of CuInS 2 (CIS) absorber layers by electrochemical procedures are presented. Starting from a simple anodic treatment in V 2+ /V 3+ electrolyte, a more complex photoelectrochemical technique is developed which consists of different consecutive etching steps for the dissolution of the predominant CuS and for the removal of remaining Cu 2 S and a small sacrificial layer of CuInS 2 . This new method also offers the possibility of in situ quality control of the CIS in a photoelectrochemical solar cell (PECS) setup. Further examination of the treated films is carried out using X-ray emission spectroscopy, X-ray photoelectron spectroscopy (XPS) and by further processing of the samples to create solid state solar cells. The specimen yield conversion efficiencies of 3.3% in PECS and 8% in solid state devices.