Issue 41, 2015

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 3LE and 3CT 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 3CT involves in RISC. Our results give insights into the spin-dependent TCA limiting the efficiency of hotly discussed CT-based OLEDs.

Graphical abstract: The triplet-charge annihilation in copolymer-based organic light emitting diodes: through the “Scattering Channel” or the “Dissociation Channel”?

Supplementary files

Article information

Article type
Paper
Submitted
23 Aug 2015
Accepted
22 Sep 2015
First published
23 Sep 2015

Phys. Chem. Chem. Phys., 2015,17, 27609-27614

Author version available

The triplet-charge annihilation in copolymer-based organic light emitting diodes: through the “Scattering Channel” or the “Dissociation Channel”?

D. Yuan, L. Niu, Q. Chen, W. Jia, P. Chen and Z. Xiong, Phys. Chem. Chem. Phys., 2015, 17, 27609 DOI: 10.1039/C5CP05016B

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