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 (Cs2CO3 1 nm/Al)提高到6.5 cd/A (Cs2CO3 3%∶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.