UV light-emitting electrochemical cells based on an ionic 2,2′-bifluorene derivative

Hsiao Fan Chen, Chih Teng Liao, Ming Cheng Kuo, Yun Shiuan Yeh, Hai-Ching Su, Ken Tsung Wong*

*此作品的通信作者

研究成果: Article同行評審

34 引文 斯高帕斯(Scopus)

摘要

UV light-emitting electrochemical cells (LECs) were, for the first time, achieved by the ionic 2,2′-bifluorene derivative, 1, which was synthesized through covalent tethering of methylimidazolium moieties as pendent groups. LEC devices incorporating ionic bifluorene 1 without (Device I) and with (Device III) the presence of poly(methyl methacrylate) (PMMA) exhibited UV EL emissions centered at 388 and 386 nm with maximum external quantum efficiencies and power efficiencies of 1.06% and 7.44 mW W-1 for Device III and 0.15% and 1.06 mW W-1 for Device I, respectively. Transmission electron microscopy (TEM) images showed that 1 tends to form nanospheres due to amphiphilic nature. The presence of PMMA unified the size of nanospheres which greatly reduced the void area in films, suppressing the current leakage and enhancing the device efficiency. Furthermore, thicker thickness of the emissive layer of LECs increases the distance between carrier recombination zone and electrodes to avoid exciton quenching. Thus, a sevenfold increase in device efficiency was obtained in thicker UV LECs containing PMMA (Device III) as compared to thinner UV LECs based on neat films of 1 (Device I). The EL emissions in the UV region are successfully achieved by LECs based on 1, which are so far the shortest emission wavelength achieved in LECs.

原文English
頁(從 - 到)1765-1773
頁數9
期刊Organic Electronics
13
發行號10
DOIs
出版狀態Published - 10月 2012

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