Melem: An efficient metal-free luminescent material

Developing efficient metal-free luminescent materials is a challenging topic because their quantum yields are usually quite low. Here, for the first time, we report a new metal-free blue-emitting melem with a high quantum yield of 56.9%. Rod-like structured melem was synthesized by treating a bulk melem with nitric acid and ethylene glycol. The quantum yield of the rod-like melem (56.9%) is about 1.6 times higher than that of the ordinary melem (35.2%) and is substantially higher than that of bulk g-C₃N₄ (4.8%), a well-known metal-free blue emission material. This promising blue phosphor, which is easy to synthesize, abundant on earth and contains no metal elements, has great potential for practical applications.