磁自旋耦合作用对OLEDs性能的影响

Performance of OLEDs Based on Magnetic Spin Coupling

介绍了近年来有关磁自旋耦合作用对有机电致发光器件性能影响的研究进展,包括有机磁阻效应、电致发光效应、光电导效应、量子效率效应等。其中,磁场作用下的有机磁阻可达到10%,理论上最大值为-50%;自旋极化注入的引入使得OLEDs的内量子效率达到32%,并且磁场作用下的电致发光强度也增强了8%左右;磁场作用下,器件的光电导和外量子效率分别增大了6%。以上效应随磁场增加逐渐趋于饱和。对于这些效应产生的理论机制,一般认为是由于三线态-三线态的猝灭、塞曼效应及超精细作用等产生的。三线态-三线态的猝灭形成了激发单线态激子S*,形成滞后的电致发光;而塞曼效应及超精细作用则认为是磁场抑制了单线态向三线态的转化致使发光增强。现在这方面的理论仍在完善过程中。

This paper summarized the progress of research on performance of OLEDs based on magnetic spin coupling in these years, including organic magnetoresistance （OMAR） effect, electroluminescence （EL） effect, photoconduction（PC） effect,quantum efficiency effect. Among these effects, the OMAR of OLEDs could achieve about 10%, even the highest up to 50% theoretically. Moreover the internal quantum efficiency of OLEDs has been improved as high as 32% because of spin polarization injecting, and the electroluminescence intensity have also been prompted as high as 8% almost under the magnetic field. The external quantum efficiency and photoconduction of OLEDs have also been improved about 6% respectively. All the effects were got under the magnetic field and were saturated with the magnetic field changing larger. For the theory mechanisms of these effects, a few studies have reported the mechanisms including TTA,Zeeman effect and hyperfine interaction（HFI）. It was argued that TTA can form additional singlet excitons and get the delayed electroluminescence（DEL）. But for Zeeman effect and hyperfine interaction（HFI）, it was showed that the magnetic field may restrain the transition between singlets and triplets,and bring the light intensity changing finally. However, the theory mechanisms still need to be enriched and proved.