基于Alq_3的有机发光二极管中的瞬时荧光与延迟荧光

Prompt fluorescence and delayed fluorescence in Alq_3-based organic light-emitting diode

制备了结构为ITO/CuPc/NPB/Alq3/LiF/Al的有机发光二极管,并在100,70,40和15K四个温度测量了器件在恒流偏置下电致发光随磁场的变化.器件的电致发光包括瞬时荧光与延迟荧光两部分.两者都可以受外加磁场影响,但对磁场的依赖关系不同.由此导出了在不同磁场强度时瞬时光强度与延迟光强度和总发光强度的关系.基于对延迟光强度磁场效应的合理估计,分别计算了器件在不同的温度、电流下瞬时光强度与延迟光强度的值,和延迟光在器件总发光中的比重.计算结果显示,在15K和160μA时,延迟光在器件总发光中的比重可超过20%.对计算公式所基于的假设进行了分析,并且探讨了这些假设对计算结果的影响.

Organic light emitting diode with structure of ITO/CuPc/NPB/Alq3/LiF/Al was fabricated,and the magnetic field effect （MFE） on electroluminescence （EL） at 100,70,40,and 15 K were measured with constant current bias.The EL of the device is composed of the prompt fluorescence （PF） and delayed fluorescence （DF）.Both of them can be modulated by an applied magnetic field,but their dependences on the magnetic field are different.Thereafter the relationships between the intensities of PF,DF,and the total EL at different B field were deduced.Basing on a suitable estimation for the MFE on DF,the intensities of PF and DF,as well as the ratio between DF and total EL,were calculated at different temperatures and currents.The results show that the proportion of DF in total EL can be higher than 20% at 15 K and 160 μA.We analyze the assumptions on which the calculation equations were obtained,and their influence on the accuracy of the results were also discussed.