Fig. 3. Optical transmittance as a function of photon wavelength for three different RGO/CNP devices. Concentrations of GO were 1 mg mL⁻¹, 0.5 mg mL⁻¹ and 0.25 mg mL⁻¹ for device 1, 2, and 3, respectively. Concentration of CNP was kept constant in all cases, which was 10⁻⁷ mol L⁻¹.