Glass-confined carbon dots: transparent afterglow materials with switchable TADF and RTP

The confined synthesis of carbon dots (CDs) in solid matrixes is a promising avenue for developing new afterglow materials. Benefiting from the advantages of the sol-gel preparation of nanoporous glass, we report transparent glass-confined CDs with tunable afterglow luminescence. Switchable thermally-activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) of CDs were achieved by adjusting the sintering temperature and ion doping. Our findings reveal that with an increase in sintering temperature from 500 °C to 600 °C, the energy gap (ΔE_ST) of CD-nanoporous glass (NG) increased from 0.05 eV to 0.21 eV, while the lifetime increased from 329 ms to 548 ms, which is attributed to the enhanced carbonization degree of the CDs. Pb²⁺ doping is also shown to achieve switchable TADF and RTP of glass-confined CDs attributed to the alteration of interfacial interactions between the glass and confined CDs. This design concept introduces a new perspective for developing transparent afterglow materials for various unique phosphorescence applications.