Intense Organic Afterglow Enabled by Molecular Engineering in Dopant-Matrix Systems.

We report intense dopant-matrix afterglow systems with an afterglow efficiency (Φ AG ) of 47% and an afterglow lifetime (τ AG ) of 1.3 s. Luminescent difluoroboron β-diketonate (BF 2 bdk) dopants and their deuterated counterparts are designed with naphthalene and carboxylic acid groups. After doping into benzoic acid (BA) matrices, room-temperature afterglow brightness and afterglow duration of the BF 2 bdk-BA materials have unexpectedly been found to reach the levels of those at 77 K, which indicates that hydrogen bonding between BF 2 bdk and BA, as well as the deuteration technique, can reduce k nr + k q of BF 2 bdk triplets to very small values even at room temperature. Detailed studies reveal that the BF 2 bdk possesses typical 1 ICT characters in the S 1 state and distinct 3 LE composition in the T 1 state, and thus shows a high Φ ISC and a small k P to obtain a high Φ AG and a long τ AG . Besides, triplet-triplet annihilation has been found in the dopant-matrix system at high doping concentrations to further increase Φ AG .