Organic LEDs promise highly efficient lighting and display technologies. We introduce a new class of linear donor-bridge-acceptor light-emitting molecules, which enable solution-processed LEDs with near-100% internal quantum efficiency at high brightness. Key to this performance is their rapid and efficient utilization of triplet states. Using time-resolved spectroscopy, we establish that luminescence via triplets occurs within 350 ns at ambient temperature, after reverse intersystem crossing to singlets. We find that molecular geometries exist at which the singlet-triplet energy gap (exchange energy) is close to zero, such that rapid interconversion is possible. Calculations indicate that exchange energy is tuned by relative rotation of donor and acceptor moieties about the bridge. Unlike other low exchange energy systems, substantial oscillator strength is sustained at the singlet-triplet degeneracy point.
|Number of pages||5|
|Early online date||30 Mar 2017|
|Publication status||Published - 14 Apr 2017|
- School of Chemistry - Professorial Fellow
- Chemistry of Light and Energy - Member
- Chemistry of Materials and Catalysis - Member
Person: Research Group Member, Academic, Teaching & Research