Thickness effect on luminescent properties of sol-gel derived ZnO thin films

► Photoluminescence of ZnO thin films grown by sol-gel technique were studied. ► The ZnO thin films are highly c-axis oriented. ► Low-temperature photoluminescence is dominated by donor-bound-exciton emission. ► The lineshape of the photoluminescence were influenced by exciton-phonon coupling. ► The exciton-phonon coupling was governed by defects in films.