Suppression of external quantum efficiency rolloff in organic light emitting diodes by scavenging triplet excitons.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 33004796.
- Also identified by DOI 10.1038/s41467-020-18292-0 and PMC identifier 7531006.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Large external quantum efficiency rolloff at high current densities in organic light-emitting diodes (OLEDs) is frequently caused by the quenching of radiative singlet excitons by long-lived triplet excitons [singlet-triplet annihilation (STA)]. In this study, we adopted a triplet scavenging strategy to overcome the aforementioned STA issue. To construct a model system for the triplet scavenging, we selected 2,6-dicyano-1,1-diphenyl-λ<sup>5</sup>σ<sup>4</sup>-phosphinine (DCNP) as the emitter and 4,4'-bis[(N-carbazole)styryl]biphenyl (BSBCz) as the host material by considering their singlet and triplet energy levels. In this system, the DCNP's triplets are effectively scavenged by BSBCz while the DCNP's singlets are intact, resulting in the suppressed STA under electrical excitation. Therefore, OLEDs with a 1 wt.%-DCNP-doped BSBCz emitting layer demonstrated the greatly suppressed efficiency rolloff even at higher current densities. This finding favourably provides the advanced light-emitting performance for OLEDs and organic semiconductor laser diodes from the aspect of the suppressed efficiency rolloff.