Suppression of external quantum efficiency rolloff in organic light emitting diodes by scavenging triplet excitons

Buddhika S.B. Karunathilaka, Umamahesh Balijapalli, Chathuranganie A.M. Senevirathne, Seiya Yoshida, Yu Esaki, Kenichi Goushi, Toshinori Matsushima, Atula S.D. Sandanayaka, Chihaya Adachi

Research output: Contribution to journalArticlepeer-review

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-λ5σ4-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.

Original languageEnglish
Article number4926
JournalNature communications
Volume11
Issue number1
DOIs
Publication statusPublished - Dec 1 2020

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

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