▎ 摘　　要

Ultraviolet (UV) ozonation is employed for making graphene photoluminescent. We find that photoluminescence (PL) varies with the ozonation temperature. For room-temperature ozonized few-layer graphene (FLG), PL is localized at the edges and in the suspended areas of FLG. At an ozonation temperature of 120 degrees C, PL localized at the edges of FLG disappears, and the surface of trilayer graphene becomes luminescent. These graphene flakes are topographically and chemically characterized to understand the origin of PL. We propose that sp(2) clusters play a key role in making graphene photoluminescent, and that intact carbon layers and charged impurities at the surface of silicon oxide substrate may quench PL. (C) 2016 Optical Society of America