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Carbon dots (CDs) with long-lived room-temperature phosphorescence (RTP) or long afterglow properties draw much attention. However, most room-temperature phosphorescent materials are metal containing, and the exploitation of long-lived color-tunable RTP materials faces great challenges. Here, we report metal-free boron-doped CDs (B-CDs) for room-temperature phosphorescence with tunable color and an ultralong lifetime. B-CDs were obtained by simply calcining a mixture of boric acid and 1,3,5-benzenetricarboxylic acid in the atmosphere. The as-prepared B-CDs were characterized through UV-vis spectroscopy, photoluminescence spectroscopy, and so forth. Under the excitation of 310 nm UV light, B-CDs show RTP that appears as blue with a phosphorescence lifetime of 1042 ms, and after switching the excited wavelength to 365 nm, the RTP appears as green with a phosphorescence lifetime of 590 ms. Due to the unique RTP properties, B-CDs display promising applications in anticounterfeiting and information encryption.
Li et al. (Fri,) studied this question.