双电子传输层对有机发光二极管效率及其衰减的改善

摘要

Efficiency and its roll-off are improved by using double electron transport layers ( DETLs) in organic light-emitting diodes ( OLEDs) . When DETLs of Bphen/BCP are employed, device effi-ciency is enhanced by 10% compared to the device with single Bphen as an electron transport layer ( ETL) because of lower hole leakage current. Meanwhile, due to more electrons injected, efficien-cy roll-off of 0% is observed for the Bphen/BCP-based device with the increase of current density from 50 to 600 mA/cm2 . On the contrast, the device with single BCP as ETL has an efficiency roll-off of 16%, which is reduced from 2. 5 cd/A at 50 mA/cm2 to 2. 1 cd/A at 300 mA/cm2 . Com-pared to the Cs2 CO3∶BCP-ETL-based device with an efficiency roll-off of 30% from 50 to 300 mA/cm2 , device efficiency is declined by 0% within the range from 50 to 600 mA/cm2 as DETLs of Bphen/Cs2 CO3∶BCP are explored. The reason is the blocking of Cs atom interdiffusion into the em-issive layer by the Bphen of Bphen/Cs2 CO3∶BCP.%采用Bphen和BCP制成双电子传输层( Double electron transport layers,DETLs)的有机发光二极管器件,与Bphen单独作ETL的器件相比, DETLs器件具有较小的空穴漏电流,效率提升10%。与BCP独自作ETL的器件相比,更多的电子注入使DETLs器件的效率在50~600 mA/cm2的电流范围内没有衰减。 BCP作ETL的器件的效率从50 mA/cm2时的2.5 cd/A衰减至300 mA/cm2的2.1 cd/A,衰减了16%。 Cs2 CO3∶BCP独自作ETL的器件效率在50~300 mA/cm2的电流范围内衰减了30%,而Bphen/Cs2 CO3∶BCP作DETLs的器件效率在50~600 mA/cm2的电流范围内衰减幅度为0,原因是Bphen阻挡了Cs原子扩散至发光层。