混合界面对溶液制备的磷光OLED器件性能的影响

摘要

利用混蒸的方法、将空穴阻挡材料2,9-Dimethyl-4,7-diphenyl-1,10-phenanhroline及电子传输材料Tris(8-hydroxy-quinolinato)aluminium混合,在电子传输层及空穴阻挡层之间制备了薄层的混合界面.在相同驱动电压下,采用混合界面的器件比常规器件的电流密度和亮度都有明显提高,在电压为10 V时,常规器件的电流密度和发光功率分别为5.13 mA·cm-2和1.03μW,而采用混合界面的器件可以分别达到18.1mA·cm-2和3.64μW.通过分析认为,引起这些提高的原因主要来自于混合界面的存在提高了电子在界面附近的传输和注入,也增大了,到达发光层的电子数目,从而增大了发光几率,引起了电流密度和发光功率的共同增长.%In the present work, in order to improve electron injection and transport at the interface of the hole blocking layer (HBL) and the electron transport layer (ETL) in the hole-domain solution processed phosphorescent organic light emitting devices (PhOLEDs), the mixed interface layer (MIL) was fabricated by partially co-doping hole blocking material 2,9-dimethyl4,7-diphenyl-1,10-phenanthroline (BCP) and electron transport material tris(8-quinolinolato) aluminum ( Alq3 ) between HBL/ETL. The MIL thickness was kept at 10nm, while the doping ratio of these two materials varied. Under a given electric field,the devices with the MIL at any mixed ratios all show much higher luminance and current density than those with a typical interface For example, the luminance power and current density at 10 V for a typical device are 1.03 μW and 5.13 mA · cm-2 ,while in case of mixed interface are 3.64 μW and 18.1 mA·cm-2, respectively. From data results and theoretical analysis, the possible derivation of these improvements is considered to be the reduced electron accumulation at the interface resulting from the reduced electron injection energy barrier and lowered transport mobility by BCP material, which leads to an increase in electron amount in the emission layer and therefore the higher luminance and current density.