利用空间电荷限制电流方法确定三(8-羟基喹啉)铝的电子迁移率特性初步研究

材料的迁移率是其关键电学特性之一.有机材料迁移率的研究对于有机电致发光器件、 有机太阳电池、有机薄膜场效应晶体管性能的提高有重要的意义. 应用简单易行的空间电荷限制电流方法,对基于三(8-羟基喹啉)铝(Alq₃) 的四种单载流子器件电流密度-电压曲线特性进行研究, 根据空间电荷限制电流模型,拟合出Alq₃材料在四种器件中的零场电子迁移率和电场依赖因子,并且给出Alq₃电子迁移率随外加偏压的变化趋势. 实验结果表明,顶电极铝蒸镀到缓冲层氟化锂(1 nm)和Alq₃ (100 nm)的表面后, 可以明显改善Alq₃的零场迁移率和电场依赖因子. 认为产生这种现象的原因是氟化锂可以使铝和Alq₃发生络合反应, 形成Li⁺¹Alq^-1粒子,形成良好的欧姆接触,使得电子的注入效率大大提高.

Preliminary investigation on the method of determining electron mobility of tris (8-hydroxyquinolinato) aluminum by space charge limited current

The charge-carrier mobility of an organic semiconducting material determines the material potential applications in devices. The investigation on mobility of organic material plays a significant role in improving the performance of organic device, such as organic light emitting diode, organic solar cell and organic thin film transistor. In this paper, we employ the space charge limited current (SCLC) method to evaluate the electron mobility of the controlled device based on tris (8-hydroxyquinolinato) aluminum (Alq₃). The zero-field mobilities and field-dependent factors of the four devices are fitted respectively. The results show that depositing Al as top-electrode onto buffer layer LiF (1 nm) and Alq₃ (100 nm) can significantly improve the the zero-field mobility and field-dependent factor of Alq₃. The reason for that is that LiF could strengthen the complex reaction between Al and Alq₃ to form Li⁺¹Alq^-1 particles, which leads to the enhanced ohmic injection and electron injection.