Single, double, and triple-coated undoped Zinc Oxide (ZnO) thin films are prepared by the traditional sol-gel spin coating technique on the quartz substrate. X-ray diffraction data of the thin films confirm that all films have hexagonal wurtzite structures. Morphological images reveal that all films have a wrinkles-like morphology due to processing conditions. The UV-VIS absorption spectra show no significant differences among the films. The optical band-gap Eg is estimated by adopting the Tauc expression and is found to be almost identical for all three films. Room temperature Photoluminescence (PL) spectra of triple-coated undoped ZnO thin film is reported which show the reduction in the visible PL intensity with increasing excitation wavelengths followed by the emergence of sharp “NBE-like” UV peak at higher excitation wavelengths. A qualitative physical model is proposed for elucidating the PL features. In the qualitative model the role of the hot energetic electrons population in the deep conduction band is invoked, whose relaxation in the defect bands have been inferred to dictate the overall luminescence mechanism.