Naphthothiadiazole‐Based Near‐Infrared Emitter with a Photoluminescence Quantum Yield of 60% in Neat Film and External Quantum Efficiencies of up to 3.9% in Nondoped OLEDs |
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| Authors: | Tengxiao Liu Liping Zhu Cheng Zhong Guohua Xie Shaolong Gong Junfeng Fang Dongge Ma Chuluo Yang |
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| Affiliation: | 1. Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan, P. R. China;2. Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, China;3. State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, China |
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| Abstract: | Fluorescent emitters have regained intensive attention in organic light emitting diode (OLED) community owing to the breakthrough of the device efficiency and/or new emitting mechanism. This provides a good chance to develop new near‐infrared (NIR) fluorescent emitter and high‐efficiency device. In this work, a D‐π‐A‐π‐D type compound with naphthothiadiazole as acceptor, namely, 4,4′‐(naphtho[2,3‐c][1,2,5]thiadiazole‐4,9‐diyl)bis(N,N ‐diphenylaniline) (NZ2TPA), is designed and synthesized. The photophysical study and density functional theory analysis reveal that the emission of the compound has obvious hybridized local and charge‐transfer (HLCT) state feature. In addition, the compound shows aggregation‐induced emission (AIE) characteristic. Attributed to its HLCT mechanism and AIE characteristic, NZ2TPA acquires an unprecedentedly high photoluminescent quantum yield of 60% in the neat film, which is the highest among the reported organic small‐molecule NIR emitters and even exceeds most phosphorescent NIR materials. The nondoped devices based on NZ2TPA exhibit excellent performance, achieving a maximum external quantum efficiency (EQE) of 3.9% with the emission peak at 696 nm and a high luminance of 6330 cd m?2, which are among the highest in the reported nondoped NIR fluorescent OLEDs. Moreover, the device remains a high EQE of 2.8% at high brightness of 1000 cd m?2, with very low efficiency roll‐off. |
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| Keywords: | aggregation‐induced emissions hybridized local and charge‐transfer state near‐infrared emitters organic light‐emitting diodes |
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