Low-Temperature Synthesis of CuInSe2 Nanotube Array on Conducting Glass Substrates for Solar Cell Application

Highly ordered arrays of Cu-rich and -deficient CuInSe2 nanotubes as well as ZnO/CuInSe2 core/sheath nanocables have been synthesized on glass substrates by using ZnO nanorod arrays as sacrificial templates via a low-cost solution method. Chemical conversions from hexagonal ZnO to cubic ZnSe, hexagonal CuSe and tetragonal CuInSe2 are demonstrated as a novel means for synthesis of I-III-VI nanomaterials. Large differences in their solubility product constant (K-sp) are crucial for direct exchange in the conversions. In solvothermal reaction of ZnO/CuSe core/shell nanocables with InCI3, the triethylene glycol solvent serves as a reducing agent for the reduction of cupric (Cu2+) to cuprous (Cu+) ions and also as an agent for the dissolution of ZnO cores. The absorption coefficient of the CuInSe2 nanotubes in the visible region is on the order of 10(4) cm(-1). Photoelectrochemical solar cells were fabricated with arrays of ZnO/Cu1.57 +/- 0.10In0.68 +/- 0.10Se2 and ZnO/CuSe nanocables. It was found that power conversion efficiency of the ZnO/Cu1.57 +/- 0.10In0.68 +/- 0.10Se2 cell is about two times higher than that based on ZnO/CuSe.