金属Rb掺杂Alq_3的电子结构及其退火与氧化行为

Annealing,oxidation and electronic structure of Alq_3 film doped with rubidium

利用同步辐射光电子能谱实验技术研究了活泼金属铷原子掺杂8-羟基喹啉铝(Rb-Alq3)薄膜的电子结构以及低温退火与氧化行为,结果表明铷和Alq3分子发生显著反应,电子从金属原子转移到Alq3的LUMO轨道,形成活泼金属/有机接触中典型的带隙态,结合能位于1.2 eV.在低温退火后,Rb-Alq3的价带往高结合能端整体位移0.1 eV,真空能级保持不变,带隙态仍然可辨;深度氧化后,带隙态消失,最高占据态(HOS)基本回到退火氧化处理前的位置,但真空能级抬高了近1 eV.Rb-Alq3氧化后的最小电离势增大了约1 eV,而纯净Alq3薄膜只增大0.05 eV左右.

The electronic structure and characteristics of annealing and oxidation of 8-tris-hydroxyquinoline aluminum （Alq3） doped with rubidium were investigated by synchrotron radiation photoemission. The results demonstrated that rubidium atoms interacted strongly with Alq3 molecules and a typical gap state, as formed at most active metal-organic contacts, appeared at binding energy of 1.2 eV via electrons of rubidium atoms doping into LUMOs of Alq3. After annealing at low temperature, the valence band of Rb- Alq3 shifted on the whole to higher binding energy by 0. 1 eV and the vacuum level kept constant, and the gap state was still distinguished clearly. While after deep oxidation of the film, the gap state disappeared and HOS recovered to where it was, yet the vacuum ionization potential （IP） of Rb-Alq3 increased by about 1 oxidation while the latter increased by only 0.05 eV. level raised approximately 1 eV. The minimum eV compared with that of pure Alq3 film after deep oxidation while the latter increased by only 0.05 eV.