Fig. 1: Afterglow systems based on phosphorescent acceptor matrixes doped with donor.

a Energy transfer diagram of room temperature phosphorescence (RTP) acceptor locally doped by donor with the compatible first singlet (S₁) and triplet (T₁) energy levels. Donor–acceptor (D-A) electronic coupling generates local dipoles featuring the low-lying singlet (¹CT^*) and triplet charge transfer (³CT^*) states. The stabilized triplet states (T_n^*) of RTP acceptors can serve as the intermediate states for energy relay to D-A dipoles, which are influenced by the energy-level order of T_n^* and ⁿCT^* (n = 1 or 3) states. ISC and RISC refer to forward and reverse intersystem crossing. The positive energy transfer based on “T_n^* > ⁿCT^*” with thermodynamic predominance to the endothermal case of “T_n^* < ⁿCT^*”. b Chemical structures of RTP acceptors nDBTxPO and donor TMB, and the corresponding highest occupied (HOMO) and lowest unoccupied (LUMO) molecular orbitals. nDBTxPO-TMB dipoles are highlighted with a dashed circle. c Photos of melt films based on nDBTxPO and nDBTxPO:1% TMB excited with UV light at 365 nm and after UV excitation for 10 s and 30 min, corresponding to time ranges for RTP enhanced by aggregation and long-persistent afterglow prolonged by D-A dipoles, respectively.