Influence of the Dielectric Constant around an Emitter on Its Delayed Fluorescence

Despite the commercial success of organic emitters based on thermally activated delayed fluorescence (TADF), a general understanding of emitter-matrix interactions is still lacking. How does the dielectric constant around an emitter impact its delayed fluorescence? The authors study the photophysical properties of three emitters in solution, showing that a higher excited triplet state at low dielectric constants can boost the efficiency of blue TADF emitters. Experiments are supported by state-of-the-art quantum simulations. The findings may be generalized to solid-state systems, pointing to tuning of host-guest architectures to improve the efficiency of TADF-based blue OLEDs.