Enhanced hole injection in organic light-emitting diodes using a SAM-derivatised ultra-thin gold anode supported on ITO glass

被引:56
作者
Hatton, RA [1 ]
Willis, MR
Chesters, MA
Rutten, FJM
Briggs, D
机构
[1] Univ Nottingham, Sch Chem, Nottingham NG7 2RD, England
[2] Univ Nottingham, Ctr Surface Chem Anal, Nottingham NG7 2RD, England
关键词
D O I
10.1039/b208169p
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
In order to increase the performance of organic light-emitting diodes (OLEDs) we report the modification of the indium-tin oxide (ITO) anode invariably used in OLEDs, with a dipolar self-assembled monolayer-derivatised (4-nitrophenylthiolate) ultra-thin gold overlayer. This composite approach allows the work function of the anode to be tuned to the hole-transporting band of the adjacent semiconductor, while facilitating good mechanical adhesion at this interface. When this modification is incorporated into the model OLED system ITO/TPD/Alq(3)/C6H5CO2Li/Al [where TPD is N,N'-bis(3-methylphenyl)-N,N-diphenyl-1,1-biphenyl-4,4'-diamine, Alq(3) is tris(quinolin-8-olato) aluminium and C6H5CO2Li is lithium benzoate], the power efficiency is dramatically enhanced. Furthermore, these devices exhibit a maximum external quantum efficiency of more than 5 cd A(-1) and a peak luminance of similar to36,000 cd m(-2). In combination with the current-voltage-luminance (LIV) characterisation of these devices, scanning Kelvin probe, polarisation modulation reflection absorption infrared spectroscopy and time of flight secondary ion mass spectroscopic techniques have been employed to probe the ITO-Au-SAM interface. This research builds on our earlier work with dipolar organosilanes, phosphonic acids and charge-transfer films at the ITO-organic interface.
引用
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页码:38 / 43
页数:6
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