We have demonstrated superstrate type nano-structured solar cells with ZnSe/ZnO coaxial NWs embedded in the CuInSe(2) (CIS) layer. Complete filling of the CIS film into the narrow spaces between the ZnO NWs was realized by growing the NWs sparsely. The ZnSe/CIS heterojunction was self-formed by converting a skin (similar to 50 nm) layer of ZnO after the selenization. The influences of the NW length and density on light trapping and on cell conversion efficiency have been investigated. A 30% improvement in J(sc) and higher efficiency has been achieved by embedding NWs in the CIS layer. Conversion efficiency of 1.79% was obtained from a ZnSe/CIS heterojunction solar cell fabricated on sparse ZnO NWs with V(oc) = 599 mV, J(sc) = 11.60 mA/cm(2) and 25.71% fill factor. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3625607] All rights reserved.