XRD pattern (a), A TEM image (b), and UV-visible absorption spectra (c) of Cu(In
NCs. Inset in (b) shows the high-resolution TEM (HRTEM) images of Cu(In0.5Ga0.5)Se2 NCs. The NCs are calculated to be approximately 17 nm in average. Insets in (c) show the image of NCs dispersed in toluene solvent and the determination of band gap of approximately 1.2 eV by direct band gap method.