標題: UV light-emitting electrochemical cells based on an ionic 2,2 '-bifluorene derivative
作者: Chen, Hsiao-Fan
Liao, Chih-Teng
Kuo, Ming-Cheng
Yeh, Yun-Shiuan
Su, Hai-Ching
Wong, Ken-Tsung
照明與能源光電研究所
Institute of Lighting and Energy Photonics
關鍵字: Light-emitting electrochemical cells;Ultraviolet;Fluorene
公開日期: 1-十月-2012
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. (c) 2012 Elsevier B.V. All rights reserved.
URI: http://dx.doi.org/10.1016/j.orgel.2012.05.050
http://hdl.handle.net/11536/20456
ISSN: 1566-1199
DOI: 10.1016/j.orgel.2012.05.050
期刊: ORGANIC ELECTRONICS
Volume: 13
Issue: 10
起始頁: 1765
結束頁: 1773
顯示於類別:期刊論文


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  1. 000309591200001.pdf