基于BAlq的有机电致发光器件的磁效应

Magnetic field effect in organic light emitting diodes based on BAlq

研究了ITO/NPB(40 nm)/BAlq(60 nm)/BCP(5 nm)/LiF(0.8 nm)/Al有机电致发光器件(OLED)的磁效应。实验结果表明,磁场在10 mT时,器件的效率最大增加了34%,这一结果是由于三线态激子与三线态激子间的相互淬灭产生激发单线态激子从而使单线态激子比率增加,致使电致发光(EL)增强。当磁场强度在10、203、04、0和50 mT时,通过器件的电流-电压特性曲线得到器件的电阻是随着磁场强度的增加而增加的。通过不同电压下器件的亮度变化率-磁感强度、效率变化率-磁感强度的关系曲线发现,器件的亮度变化率和效率变化率随磁场强度的增加而降低,这是由于单重态极化子对在电场和磁场作用下解离为二次自由载流子并在势垒界面处积累所造成的。

The current and electroluminescence（EL） of magnetic field dependent organic light-emitting diode（OLED） with the structure of ITO/NPB（40 nm）/BAlq（60 nm）/BCP（5 nm）/LiF（0.8 nm）/Al were measured at room temperature.It has been found that the efficiency increases by up to 34% as the magnetic field increases to 10 mT,which suggests that the increase of device efficiency is due to the conversion of triplets into singlets through triplet-triplet annihilation.The current-voltage characteristic curves show that the resistances of devices increase with magnetic field increasing from 10 mT to 50 mT.In addition,the luminescence change ratio and the efficiency change ratio are decreased with increasing magnetic field,which is because the singlet polaron-pairs are regenerated to the secondary charge carriers,and are accumulated at the potential barrier interface.