Covalent Bonding Enhanced Structural Rigidity for Boosted Heavy Atom-Free Room-Temperature Phosphorescence

To enhance the structural rigidity of heavy atom-free room-temperature phosphorescence (RTP) materials, crystallization engineering via molecular stacking has been proposed. However, the current strategies generally rely on noncovalent interactions, which are nondirectional for structural regulation and susceptible to break under complex environmental conditions. Herein, we have proposed the B–O click reaction between boronic acid and hydroxyl groups to promote the structural rigidity of chromophores. The crystallization behaviors of chromophores with boronic acid groups have been effectively regulated with the addition of ethylene glycol, and the established B–O covalent network provided a rigid environment to suppress the nonradiative transition of chromophores. Accordingly, boosted RTP performances with prolonged lifetime as well as decent stability have been achieved for the heavy atom-free composites. Such a B–O covalent network could be applied for different chromophores, showing great potential for practical applications in information encryption.