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

研究成果: ジャーナルへの寄稿学術誌査読

8 被引用数 (Scopus)

抄録

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.

本文言語英語
論文番号185501
ジャーナルJournal of Applied Physics
126
18
DOI
出版ステータス出版済み - 11月 14 2019

!!!All Science Journal Classification (ASJC) codes

  • 物理学および天文学(全般)

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