Origin of external quantum efficiency roll-off in 4,4′-bis[(N -carbazole)styryl]biphenyl (BSBCz)-based inverted organic light emitting diode under high pulsed electrical excitation

F. Bencheikh, A. S.D. Sandanayaka, T. Fukunaga, T. Matsushima, C. Adachi

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Laser diodes based on organic semiconductor materials have high threshold current densities that require the suppression of various inherent loss processes. One way to study such loss processes is to analyze the external quantum efficiency (EQE) roll-off in organic light-emitting diodes (OLEDs). In this work, we used electrical simulations to analyze the origin of the experimental EQE roll-off of an OLED based on 4,4′-bis[(N-carbazole)styryl]biphenyl (BSBCz) under extremely high current injection (∼1 kA/cm2). We considered various singlet exciton annihilations and quenching processes (i.e., singlet-singlet annihilation, singlet-triplet annihilation, singlet-polaron annihilation, singlet-heat quenching, and electric field quenching of singlet excitons). These results showed that the EQE roll-off can be attributed to Joule heating and/or singlet-triplet annihilation and/or the dissociation of singlet excitons under a high applied electric field. The electric field quenching of singlet excitons was confirmed by a field-induced photoluminescence (PL) quenching experiment. By applying an electric field-induced charge dissociation model to both the EQE and field-induced PL quenching, we estimated the singlet exciton binding energy of a BSBCz film to be in the range of 0.64-0.71 eV.

Original languageEnglish
Article number185501
JournalJournal of Applied Physics
Volume126
Issue number18
DOIs
Publication statusPublished - Nov 14 2019

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Fingerprint Dive into the research topics of 'Origin of external quantum efficiency roll-off in 4,4′-bis[(N -carbazole)styryl]biphenyl (BSBCz)-based inverted organic light emitting diode under high pulsed electrical excitation'. Together they form a unique fingerprint.

Cite this