Growth of CuInSe₂ and In₂Se₃/CuInSe ₂ 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. In ₂Se₃/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 In₂Se ₃/CuInSe₂ nano-heterostructures.