Abstract:

Organic luminescent materials are promising for next-generation flexible optoelectronics. Nonetheless, the luminescent efficiency in organic molecules is limited by a barrier between the singlet and triplet excited states. In this mini review, we focus on the strategies to overcome such limit by manipulating the dynamics of triplet excited states. By designing the electronic coupling between singlet and triplet excited states, the processes of hot intersystem crossing, reversal intersystem crossing and triplet state stabilization at different stages are successfully implemented to promote the light emission in the organic luminescent materials. The understanding of the mechanisms drives the development of thermally-activated delayed fluorescence and organic long-persistent luminescence, which are promising for the applications of organic light-emitting diodes, sensors and bioimaging.

Key words: organic luminescent material, triplet excited state, charge transfer state, charge separated state, hot exciton, hot intersystem crossing, reverse intersystem crossing, triplet state stabilization, thermally activated delayed fluorescence, long persistent luminescence, organic light-emitting diode