Effect of surface groups on the luminescence property of ZnO nanoparticles synthesized by sol-gel route

► In this study we examine the origin of green luminescence (GL) emission in ZnO nanoparticles by PL spectroscopy. ► Hydroxyl groups attached to the surface of ZnO nanoparticles are responsible for GL emission in atmospheric condition. ► In vacuum condition, native defects give rise to the remnant GL emission.