title: The triplet-charge annihilation in copolymer-based organic light emitting diodes: through the "Scattering Channel" or the "Dissociation Channel"?
abstract: In organic semiconductors, the triplet-charge annihilation (TCA) is one of the most common excitonic interactions influencing the opto-electronic power conversion efficiency of the devices. However, it is still unclear whether the TCA reaction goes through the "Scattering Channel" or the "Dissociation Channel". In this work, by measuring the organic magneto-current (OMC) of the conjugated co-polymer poly[{9,9-dioctyl-2,7-divinylene-fluorenylene}-alt-co-{2-methoxy-5-(2-ethylhexyloxy)-1,4-phenyene}] (PFOPV)-based organic light-emitting diodes (OLEDs) containing both localized exciton (LE) and charge-transfer-complex (CT), it is found that (3)LE and (3)CT play a crucial role in the "Scattering Channel" and the "Dissociation Channel" of TCA, respectively. This argument was supported by the simulations of Lorentzian and non-Lorentzian functions used, respectively, for intersystem crossing (or reverse intersystem crossing, RISC) and TCA effects. Moreover, by inserting a tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane (3TPYMB) layer between PFOPV and the cathode, we improved the electroluminescence efficiency of PFOPV-based OLEDs by suppressing the TCA when (3)CT involves in RISC. Our results give insights into the spin-dependent TCA limiting the efficiency of hotly discussed CT-based OLEDs.
authors.affiliation: School of Physical Science and Technology, MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University, Chongqing 400715, P. R. China. chenping206@126.com zhxiong@swu.edu.cn.
authors.forename: De
authors.initials: D
authors.lastname: Yuan
authors.forename: Lianbin
authors.initials: L
authors.lastname: Niu
authors.forename: Qiusong
authors.initials: Q
authors.lastname: Chen
authors.forename: Weiyao
authors.initials: W
authors.lastname: Jia
authors.forename: Ping
authors.initials: P
authors.lastname: Chen
authors.forename: Zuhong
authors.initials: Z
authors.lastname: Xiong