A Simple and Universal Approach to Synthesizing Multi-Confined Carbon Dots with Thermally Activated Delayed Fluorescence.

Afterglow materials possess the remarkable capability to harness the energy and subsequently emit light after irradiation is turned off. Owing to their extraordinary ultralong lifetime, afterglow materials have garnered significant interest across various domains such as sensing, optoelectronics, bioimaging, and information encryption. However, these materials typically exhibit temperature sensitivity, rendering their afterglow emission susceptible to efficient quenching at room temperature. Consequently, this study presents herein a straightforward, simple, and universal approach for synthesizing metal-free carbon dots (CDs) endowed with thermally activated delayed fluorescence (TADF) characteristics at room temperature. In this study, TADF-CDs were simply synthesized by pyrolyzing boronic acid (BA) and urea at 500 ℃ for 3 h. Benefiting from the multi-confined effects facilitated by the robust structure of BA matrix, in conjunction with the co-doped heteroatoms of nitrogen and boron, the resultant TADF-CDs manifest remarkably prolonged afterglow TADF emission, characterized by a calculated lifetime of 184.64 ms; moreover, the blue afterglow emission remains perceptible to the naked eye for more than 6 s. The attributes of TADF-CDs were comprehensively elucidated through rigorous characterization, and the universality of the approach was corroborated through experimentation involving fourteen control CDs. Leveraging their distinctive TADF attributes, the prepared TADF-CDs were subsequently employed in advanced applications such as anti-counterfeiting and information encryption.