Microstructural, Optical, and Work Function Tuning of Fullerene (C60) Modified Zinc Oxide Films for Optoelectronic Devices

Abstract

Here, we report the synthesis of pristine and fullerene (C60) modified zinc oxide (ZnO) films by the sol-gel method. Various compositions of C60 ranging from pristine to 0.25 wt%, 0.50 wt%, and 1.00 wt% have been chosen for the modification of ZnO film. The incorporation of C60 in pristine ZnO films modifies its structural, surface morphological, optical, and electrical properties. Structural characterization suggests that pristine and C60 modified ZnO films exhibit Wurtize crystal structure. Surface morphological characterization demonstrates that incorporation of C60 into ZnO leads to the formation of spherical nano-particles which varies on the doping of C60. The properties of C60 doped ZnO films show a reduction in the bandgap values from 3.11 eV to 2.73 eV with enhanced optical absorption and photoluminescence properties. Further, the surface potential and work function of pristine and C60 incorporated ZnO films, as investigated by Kelvin probe force microscopy (KPFM) show tuning of Fermi level in pristine and C60 modified ZnO films. The work function of the ZnO films changes from −4.38 eV to −4.46 eV on the incorporation of C60. The variations in work function may be due to reduced microstructural and localized defects offered during the incorporation of C60. Also, C60 modified ZnO Schottky diodes exhibited enhanced carrier mobility with better charge transport properties.