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 InCl₃, 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 10⁴ cm^-1. Photoelectrochemical solar cells were fabricated with arrays of ZnO/Cu _1.57±0.10In_0.68±0.10Se₂ and ZnO/CuSe nanocables. It was found that power conversion efficiency of the ZnO/Cu_1.57±0.10In_0.68±0.10Se₂ cell is about two times higher than that based on ZnO/CuSe. © 2010 American Chemical Society.