LiF插层对有机发光二极管磁场效应的调控

制备了有LiF插层的有机发光二极管，以八羟基喹啉铝（Alq₃）作为电子传输层，N, N′-二苯基-N, N′-二(1-萘基)-1,1′-联苯-4,4′-二胺（NPB）作为空穴传输层.通过改变Alq₃与NPB间LiF插层的厚度，研究了不同温度下器件的光电特性及电致发光的磁场效应.测量结果表明:LiF插层可以影响器件内部载流子的输运和激发态的形成.较厚的插层阻碍了空穴的传输，使器件的电流效率变低.但实验中发现，关键词：LiF插层结构磁场效应三重态激子

Tuning effect of magnetic-field in organic light emitting diodes using LiF layer

The organic light emitting diode with inserted LiF layer has been fabricated. Tris-(8-hydroxyquinoline) aluminum (Alq₃) was used as electron-transport layer and N, N′-bis(1-naphthyl)-1,1′-biphenyl-4,4′-diamine (NPB) was used as hole-transport layer. By changing the thickness of LiF deposited between Alq₃ and NPB, the optoelectrical properties and the magnetic field effect on electroluminescence were studied at different temperatures. The measurement results show that using LiF layer enables the transport of carrier and the formation of excited states inside the device. A thick LiF layer blocks the transport of holes, lowering the efficiency of the device. However, use of LiF layer can effectively tune the magnetic field effect of electroluminescence. Compared with conventional devices, the magnetic field effect of device with inserted LiF layer was strengthened within low-field range (the magnetic induction B<40 mT) at different temperatures. At low temperatures, inserting LiF layer significantly weakens the magnitude of high-field (B≥40 mT) decrease of electroluminescence, and the thicker the LiF layer, the smaller the magnitude of decrease. These observations indicate that the concentration of the triplet excitons offects the high magnetic field decrease of electroluminescence at low temperatures.