有机多层量子阱结构的光致发光特性的研究

采用多源高真空有机分子束沉积系统(OMBDs)，将两种有机小分子材料PBD和Alq₃以交替生长的方式，制备了不同厚度的PBD/Alq₃有机多层量子阱结构(OMQWs), 并利用电化学循环伏安法和光吸收分别测定了PBD和Alq₃的最低空分子轨道(LUMO)和最高占据分子轨道(HOMO)。该结构类似于无机半导体中的Ⅰ型量子阱结构，PBD层作为势垒层，Alq3层作为势阱层和发光层，并进行了小角X射线衍射(XRD)的测量。利用荧光光谱研究了OMQWs光致发光(PL)特性，得到随着阱层厚度的降低，光致发光的峰位将蓝移;同时随垒层厚度的减小，PBD的发光峰逐渐消失。利用量子阱结构可以使PBD的能量有效的传递给Alq₃,从而增强Alq₃的发光。

The Photoluminescence Characteristics of Organic Multilayer Quantum Wells

By the use of multi-source high-vaccum organic beam deposition system, the authors prepared organic multilayer quantum well structures, which consist of alternate organic small molecule materials PBD and Alq3. Based on 4-period organic quantum wells, different samples with different thickness barriers and wells were prepared. The authors measured the lowest unoccupied molecular orbit (LUMO) and the highest occupied molecular orbit (HOMO) by electrochemistry cyclic voltammetry and optical absorption. From the energy diagrams, it seems like type-I quantum well structures of the inorganic semiconductor, in which PBD is used as a barrier layer and Alq3 as a well layer and emitter. From small angle X-ray diffraction measurements, the results indicate that these structures have high interface quality and uniformity. The photoluminescence characteristics of organic multilayer quantum wells were investigated. The PL peak has a blue-shift with the decrease of the well layer thickness. Meanwhile as the barrier thickness decreases the PL peaks of PBD disappear gradually. And the energy may be effectively transferred from PBD to Alq3, inducing an enhancement of the luminescence of Alq3.