Materials exhibiting thermally activated delayed fluorescence (TADF) are heralded as next generation emitters for organic light-emitting devices (OLEDs). Their narrow singlet-triplet energy gaps (ΔEST) are typically achieved through intramolecular charge transfer (ICT) and enable triplet harvesting. The crucial problem facing these materials is obtaining a high photoluminescence quantum yield (PLQY) alongside rapid reverse intersystem crossing (rISC) in the same material. A high PLQY is vital for good efficiency; and has been enhanced to 100% in numerous emitters. However, this is always to the detriment of fast rISC, which is essential for OLED stability at both high brightness and in the long term.<br/>We recently introduced a new structural class of 3D molecule capable of ICT, based upon an electron poor ring-fused triptycene core. The three fused benzene ‘‘fins’’ of triptycene are able to communicate through the spatial overlap of their molecular orbitals, termed homoconjugation. We showed that homoconjugation facilitates a great increase in ICT oscillator strength and a narrowing of ΔEST compared to a single fin, without a red shift in PL.<br/>We have now extended this concept to ICT TADF triptycenes. We will present results showing that homoconjugation enables an increase in ICT oscillator strength alongside enhanced rISC to tackle the greatest problem facing TADF.

Homoconjugation enhances luminescence and reverse intersystem crossing in thermally activated delayed fluorescent triptycenes

ACS Fall 2020 Virtual Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.