Spatial donor/acceptor architecture for intramolecular charge-transfer emitter

A folded molecular construction, in which electron donor and acceptor can interact each other to give bright luminescence. And thermally activated delayed fluorescence device with ∼20% external quantum efficiency is achieved with this emitter. [Display omitted] Charge transfer via electron hopping from an electron donor (D) to an acceptor (A) in nanoscale, plays a crucial role in optoelectronic materials, such as organic light-emitting diodes (OLEDs) and organic photovoltaic cells (OPVs). Here, we propose a strategy for binding D/A units in space, where intramolecular charge-transfer can take place. The resulted material DM-Me-B is able to give bright emission in this molecular architecture because of the good control of D/A interaction and conformational rigidity. Moreover, DM-Me-B presents small singlet-triplet splitting energy, enabling thermally activated delayed fluorescence. Therefore, the DM-Me-B exhibits ∼20% maximum external quantum efficiency and low efficiency roll-off at 1000 cd/m2, certifying an effective strategy in controlling D/A blocks through space.