Broad band photoluminescence of g-C3N4/ZnO/ZnS composite towards white light source

Highlights: • g-C₃N₄/ZnO/ZnS composite was synthesized by one-step pyrolytic method. • g-C₃N₄/ZnO/ZnS photoluminescence studied in temperature range 10–300 K. • photoluminescence of the g-C₃N₄ red shifts with increase of synthesis temperature. • g-C₃N₄/ZnO/ZnS synthesized at temperatures 600–625 °C exhibit white luminescence. We have found one step synthesized g–C₃N₄/ZnO/ZnS composite to be promising for engineering of white-light sources. The composite was fabricated by simultaneous pyrolytic decomposition of thiourea and zinc acetate with a consequent in situ polymerization of the products at 550–625 °C and characterized by SEM, XRD, EDX and low temperature PL spectroscopy. The composite synthesized at 550 °C demonstrates blue PL with a peak at 2.74 eV while higher temperatures of the synthesis result in a broad spectra with a maximum at 2.22 eV and comprise of the bands of g–C₃N₄ and mixed ZnO/ZnS as they have been resolved by low temperature PL. The proper selection of the synthesis temperature allows an extension of light emitting spectra of g–C₃N₄/ZnO/ZnS composites from blue to white light range. The results obtained show ternary systems containing g-C₃N₄ and wide band-gap semiconductors are suitable for white-light emitting and optoelectronic devices.