Employing Cholesterol Copolymerization Strategy for a Thermally Processable Organic Room-Temperature Phosphorescence Material

Development of pure organic room-temperature phosphorescent (RTP) materials with strong emission and decent processability is highly desirable. However, in the pursuit of high quantum yield (QY) of phosphorescence, the processability of RTP materials is suppressed unwarily. Here, a liquid crystalline (LC) copolymer is envisioned, NpA-Chol, comprising bromonaphthalimide as the phosphor and cholesterol as the LC mesogen. NpA-Chol exhibits LC flexibility at high temperatures, thus enabling the material to possess decent processability. In addition, the liquid crystallinity of NpA-Chol could be improved remarkably after thermal annealing, making a 7.5-fold increase in phosphorescence QY. This cholesterol copolymerization strategy paves a general avenue for addressing the major defect well: highly efficient RTP materials always suffer from suppression of thermal processability.

Automated summary

A novel liquid crystalline copolymer, NpA-Chol, combining phosphor bromonaphthalimide and cholesterol as mesogen, shows good processability and significantly improved phosphorescence quantum yield after thermal annealing. This cholesterol copolymerization strategy offers a new approach to overcoming the common issue of reduced thermal processability in highly efficient RTP materials.