Growth of CuInSe2 and In2Se3/CuInSe2 Nano-Heterostructures through Solid State Reactions

In2Se3 is an essential phase change material and CuInSe2 is the fundamental basis of the copper-indium-gallium-diselenide (CIGS) solar energy material. In this paper, we demonstrate the feasibility to transform the phase change material to the solar energy material via the solid state reaction. The In2Se3 nanobelts (NBs) were synthesized via the vapor-liquid-solid mechanism. The chemical composition and the optical properties were investigated by energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and reflectance and photoluminescence spectra. In the in situ observation of the solid state reaction with Cu to form the CuInSe2 NBs with ultrahigh vacuum transmission electron microscopy, we observed the In2Se3/CuInSe2 transformation at atomic scale in real time. The progression of the atomic layer at the interface provided the pertinent information on the kinetic mechanism. In2Se3/CuInSe2 nano-heterostructures were also obtained in the present investigation. The approach to the CIGS nanosolar cell was also proposed. This study shall be beneficial in the development of high-performance nanowire solar cells and nanodevices with In2Se3/CuInSe2 nano-heterostructures.