標題: Tailoring balance of carrier mobilities in solid-state light-emitting electrochemical cells by doping a carrier trapper to enhance device efficiencies
作者: Liao, Chih-Teng
Chen, Hsiao-Fan
Su, Hai-Ching
Wong, Ken-Tsung
照明與能源光電研究所
Institute of Lighting and Energy Photonics
公開日期: 2011
摘要: We demonstrate the improving balance of carrier mobilities in neat-film light-emitting electrochemical cells (LECs) utilizing a cationic transition metal complex (CTMC) as the emissive material and a cationic near-infrared laser dye as the carrier trapper. This low-gap carrier trapper is judiciously chosen such that a significant energy offset in the highest occupied molecular orbital (HOMO) levels between the CTMC and the carrier trapper impedes hole transport in the emissive layers while similar lowest unoccupied molecular orbital (LUMO) levels of these two materials result in relatively unaffected electron transport. Since the CTMC neat films would intrinsically exhibit characteristics of preferred transport of holes, the balance of carrier mobilities would be improved by doping such carrier trapper. Electroluminescent measurements show that the peak external quantum efficiency (EQE) and the peak power efficiency of the neat-film LECs doped with the carrier trapper reach 12.75% and 28.70 lm W(-1), respectively. These device efficiencies represent a 1.4 times enhancement as compared to those of the undoped neat-film LECs and approach the upper limit of EQE (similar to 15%) that one would expect from the photoluminescence quantum yield of the emissive layer (similar to 0.75) and an optical out-coupling efficiency of similar to 20% from a typical layered device structure, consequently indicating superior balance of carrier mobilities in such a doped emissive layer. These results confirm that the balance of carrier mobilities in the CTMC neat films would be improved by doping a proper carrier trapper and this technique offers a general approach for optimizing device efficiencies of CTMC-based neat-film LECs.
URI: http://hdl.handle.net/11536/14816
http://dx.doi.org/10.1039/c1jm13245h
ISSN: 0959-9428
DOI: 10.1039/c1jm13245h
期刊: JOURNAL OF MATERIALS CHEMISTRY
Volume: 21
Issue: 44
起始頁: 17855
結束頁: 17862
顯示於類別:期刊論文


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  1. 000296390600046.pdf