高分子基质调控室温磷光效率的设计策略

Design Strategy of Polymer Matrix to Regulate Room Temperature Phosphorescence Efficiency

高分子常作为有机磷光剂的刚性基质抑制非辐射跃迁来获得室温磷光.然而,以往研究偏于强度高分子玻璃化转变温度和自由体积如何影响室温磷光,关于基质与磷光剂之间的电子耦合如何调控室温磷光却鲜有研究.本文尝试将-种基于芳香酮磷光剂的单体与其他四种不同的基质单体共聚来解决这样的问题,得到的共聚物展现具有基质依赖性的室温磷光效率:当基质与磷光剂的电子耦合逐渐增强时,室温磷光效率由最高的22%降低至0%,表明磷光剂的三线态能级与基质相近时,容易通过电子交换机制耗散三线态激发态能量.

Polymers are routinely used as embedding matrices for organic molecular phosphors to substantially reduce the non-radiative decay rate and promote room-temperature phosphorescence(RTP).However,most previous studies focus on how glass transition temperature and free volume of various polymers influence RTP efficiency;very little is known on how electronic coupling between the matrix and the phosphor can modulate organic RTP.In the current investigation,we attempt to address the issue by synthesizing a monomeric version of an aromatic ketone phosphor and copolymerizing the ketone with four different types of matrix monomers.The resulting copolymers exhibit clear matrixdependent RTP efficiency:a gradual decrease of RTP quantum yield from 22%to nearly 0 can be observed when the electronic conjugation of the matrix increases,suggesting that energy dissipation can occur in the triplet excited state via electron exchange when the triplet state of the matrix is close to that of the phosphor.The study provides a guiding principle on regulating the lifetime of triplet-excited states for organic dyes.