Li掺杂8-羟基喹啉铝的密度泛函理论研究

摘要

采用密度泛函理论研究了Li原子掺杂8．羟基喹啉铝（Alqa）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Alqa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Alqa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Alqa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：l左右的比例。%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 Alqa 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.