An In(x)(OOH,S)(y)/CdS double layer was utilized as a heterojunction counterpart in CdTe solar cells to enhance the transmission of light through the window layer. An In(x)(OOH,S)(y)/CdS double layer was deposited by chemical bath deposition onto an ITO-coated Corning glass substrate in varying thickness combinations. In(x)(OOH,S)(y), is porous, and the interface between the In(x)(OOH,S)(y), and CdS layers overlaps to a large extent. The In(x)(OOH,S)(y)/CdS double layer showed a higher optical transmittance in the 500-600 nm wavelength range compared to the CdS layer. However, the efficiency of In(x)(OOH,S)(y)/CdS/CdTe solar cells was not improved due to the lower open circuit voltage. It is considered that the In(x)(OOH,S)(y)/CdS window layer is less n-type, which is most likely due to the mixing of the two layer during CdTe deposition at 575 degrees C. (C) 2008 Elsevier B.V. All rights reserved.