Issue 27, 2015

Simultaneous harvesting of triplet excitons in OLEDs by both guest and host materials with an intramolecular charge-transfer feature via triplet–triplet annihilation

Abstract

A red naphthalimide derivative with an intramolecular charge-transfer (ICT) feature, namely (E)-2-(4-(t-butyl)phenyl)-6-(2-(6-(diphenylamino)naphthalen-2-yl)vinyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (NA-TNA), was designed and synthesized. Photophysical and magneto-electroluminescence (MEL) characterization results revealed that NA-TNA could harvest triplet excitons via a triplet–triplet annihilation (TTA) process in organic light-emitting diodes (OLEDs) due to the presence of a lower-lying triplet excited state with 3ππ* character. Consequently, using NA-TNA as a guest compound and CzPhONI, another ICT-featured naphthalimide derivative with triplet fusion delayed fluorescence (TFDF) character as host material, a high-performance orange OLED with 6 wt% NA-TNA doped CzPhONI film as the emitting layer was acquired. The maximum current efficiency (LEmax), brightness (Lmax), and external quantum yield (EQEmax) of this OLED is 7.73 cd A−1, 31 940 cd m−2 and 5.83%, respectively, while the theoretical EQEmax of this device should not exceed 3.34%. On the contrary, the reference device with a NA-TNA doping level of 1.4 wt% showed much inferior performance, with a LEmax, a Lmax, and an EQEmax of 3.19 cd A−1, 24 900 cd m−2 and 2.49%, respectively. The high performance of the 6 wt% NA-TNA doped device was attributed to the efficient harvesting of triplet excitons by both the guest and host materials.

Graphical abstract: Simultaneous harvesting of triplet excitons in OLEDs by both guest and host materials with an intramolecular charge-transfer feature via triplet–triplet annihilation

Supplementary files

Article information

Article type
Paper
Submitted
20 Mar 2015
Accepted
21 May 2015
First published
21 May 2015

J. Mater. Chem. C, 2015,3, 6970-6978

Author version available

Simultaneous harvesting of triplet excitons in OLEDs by both guest and host materials with an intramolecular charge-transfer feature via triplet–triplet annihilation

X. Zheng, Q. Peng, J. Lin, Y. Wang, J. Zhou, Y. Jiao, Y. Bai, Y. Huang, F. Li, X. Liu, X. Pu and Z. Lu, J. Mater. Chem. C, 2015, 3, 6970 DOI: 10.1039/C5TC00779H

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