Li掺杂8-羟基喹啉铝的密度泛函理论研究

采用密度泛函理论研究了Li原子掺杂8-羟基喹啉铝(Alq₃)分子的几何构型、 前线分子轨道及电子转移特性. 研究结果表明, Li原子掺杂Alq₃后, Li原子与Alq₃的O, N原子键合, 形成电子转移复合物. Li原子将部分电子转移到Alq₃的吡啶环上, 在Alq₃的带隙内形成施主能级, 这种n型掺杂结构有效地提高了电子的传输效率; 但过多的Li原子的掺杂会使Alq₃分解, 从而减弱其电子传输能力. 为使Alq₃的电子传输能力达到最高, Li原子的掺杂应保持在2:1左右的比例.

Lithium-doped tris (8-hydroxyquinoline) aluminum studied by density functional theory

The geometry, the frontier molecular orbital and the charge transfer property of lithium (Li) doped tris (8-hydroxyquinoline) aluminum (Alq₃) are investigated by the density functional theory (DFT) method. The calculated results show that in the Li-doped Alq₃ system, Li-N and Li-O bonds are formed and Li-Alq₃ electron transfer complexes are obtained. The incomplete electron transfer from Li atoms to the pyridine side of Alq₃ results in donor level in the band gap of Alq₃, a typical n-type doping formation, which can improve efficiently the electron transport efficiency. However heavy Li doping can induce the dissociation of Alq₃, which leads to the decline of electron transport ability. When the Li:Alq₃ doping ratio is about 2:1, the Li-doped Alq₃ layer will have a maximal electron transport efficiency.