Cs2CO3共蒸阴极对有机电致发光器件性能的影响(英文)

A Novel Electron Injection Layer with Co-evaporating Tris(8-hydroxyquinoline) Aluminum Doped Cesium Carbonate in Organic Light-emitting Diodes

研究了碳酸铯(Cs2CO3)掺杂8-羟基喹啉铝(Alq3)作为电子注入层对有机电致发光器件性能的影响。结果表明,与常用的Cs2CO3超薄层作电子注入层相比,Cs2CO3∶Alq3共蒸阴极对器件效率和亮度有很大提高,器件电流效率从3.1 cd/A(Cs2CO31 nm/Al)提高到6.5 cd/A(Cs2CO33%∶Alq3/Al)。器件性能的提高归因于Cs2CO3∶Alq3共蒸阴极比单层Cs2CO3阴极具有更好的电子注入能力和电子传输性能。薄膜形貌表明,共蒸阴极能有效降低Alq3表面粗糙度,有助于提高器件发光性能及寿命。

The electron injection mechanism of the effective cathode structure has been investigated,doping cesium carbonate（Cs2CO3） into the organic electron-transport layer,which significantly enhances the electron injection in comparison with an ultra-thin Cs2CO3 injection layer,with a notable superiority in both luminance and efficiency.The results show that Cs2CO3 doped tris-（8-hydroxyquinoline） aluminum（Alq3） /Al cathode exhibits better electron injection efficiency than that in Cs2CO3/Al bilayer cathode,thus a maximum current efficiency of 6.5 cd/A（3.1 cd/A for Cs2CO3/Al） is obtained for 30% Cs2CO3 doping concentration device.It is proposed that this improved efficiency is related to the greatly enhanced electron injection at the Alq3∶Cs2CO3/Al cathode interface and efficient electron transport in the bulk of the Cs2CO3∶Alq3 layer.The result from atomic force microscopy shows that with the insertion of Alq3∶Cs2CO3 layer,the roughness of Alq3 surface decreases,which is favorable to improve the device luminance and increase the device lifetime.