Fig. 6. Optical properties study using the DRS-UV-vis spectroscopic technique and Kubelka–Munk function analysis: (a) % reflectance versus wavelength plot of ZnO and GCD-Z10.5 NCs, with greater light harvesting behaviour for the GCD-Z10.5 NCs. (b) Kubelka–Munk function plots: (inset labels i and ii) direct and (inset labels iii and iv) indirect Kubelka–Munk plots for ZnO and GCD-Z10.5 NCs, respectively. Redshift for both direct and indirect GCD-Z10.5 plots confirms the inclusion of copper in the ZnO lattice of GCD-Z10.5.
