Effect of aging time on the optical, structural and photoluminescence properties of nanocrystalline ZnO films prepared by a sol–gel method

•The ZnO crystalline film has been deposited onto quartz substrates by a sol–gel method at different aging time (0 to 11 days).•The deposited films are highly transparent with an average transmission exceeding 82–95% in the visible range (400–800nm), which slightly improved with aging time.•The enhancement of the PL intensity near UV and visible region with aging time suggests that these films can be used for photoluminescence applications. The nanocrystalline zinc oxide (ZnO) films were deposited by a sol–gel method and the effect of sol aging time 0, 1, 7 and 11 days on the structural, optical and photoluminescence properties were investigated. X-ray diffraction analysis showed that the deposited films were polycrystalline with hexagonal wurtzite structure and high orientation along c-axis direction. The grain size was in the range of 42–60nm increased with sol aging time also the thickness increased from 70 to 147nm with the aging time increment. The roughness of ZnO film investigated by atomic force microscope showed that roughness of the films increased then decreased with the increment of the aging time. The deposited films are highly transparent with an average transmission exceeding 82–95% in the visible range (400–800nm), which slightly improved with aging time. The measured optical band gap values of the ZnO films were between 3.1eV and 3.6eV. The photoluminescence intensity increased with the aging time and the ZnO films have ultraviolet, violet and green emission.