Copper-Doped Zinc Oxide Nanoparticles for the Fabrication of white LEDs

Abstract

Zinc oxide (ZnO) is the most commonly and widely studied material in the field of nano science and technology due to its unique characteristics, such as wide band gap energy (3.37 eV), electrical and thermal stability, large exciton binding energy (60 meV), biocompatibility and biosafety. Copper is considered as an important dopant for ZnO due to their almost similar ionic radii which enhances the properties of ZnO. Thus, pure and copper-doped nanocrystalline ZnO particles were synthesized through sol–gel approach in the current study. The concentration of the dopant is varied from (0.1–0.3%) and the composition, structural and optical characterizations were performed by using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, UV-Vis optical absorption and photoluminescence (PL) spectrometer. The structural analysis confirmed that copper ions substitute Zn ions without altering their wurtzite structure and a crystallite size of 10–16 nm with high degree of crystallization. Morphological properties conducted using SEM confirmed copper doping strongly influenced the grain size and morphology of ZnO NPs. Moreover, the morphology variation is observed from spherical nanoparticles to nanorods with Cu (0.2%) doping into host matrix. The morphological variation may be attributed to strong influence of Cu ions on the growth rate of ZnO. PL measurement had been carried out at room temperature in which high intensity broad emission peaks were observed in visible region around 450–700 nm that indicates the superposition of green and yellow-orange emission bands. Currently, light-emitting diodes (LEDs) giving green light emission have been combined with broad-band visible phosphors to make white-light LEDs. Thus, green photo luminescent copper-doped ZnO nanoparticles from the current study is highly significant in the fabrication of white-light LEDs.