摘要
有机电致发光材料能带的准确测定对于有机电致发光器件研究至关重要。电化学方法(如循环伏安法)是表征有机材料的HOMO能级的简单而被广泛采用的方法。通常所用循环伏安法存在用料多、数值确定不明显等方面的缺点,因此我们改进了上述方法,将待测定材料在工作电极上成膜,采用线性扫描伏安法直接测定氧化电流起峰位置而得到其HOMO能级。再结合光谱数据就可以计算出材料的LUMO能级。研究表明该方法用料量少、快速、简便。
In multi-layered organic electroluminescent devices, it is very important to obtain accurate data of energy band structure of organic electroluminescent materials. There are mainly several methods, for example, UV-vis absorption spectroscopy, quantum chemistry calculation, and cyclic voltammetry, are usually used to obtain band gap and HOMO energy level, respectively. However it is too difficult to get precise data of HOMO energy level by cyclic voltammetry. In this paper technology of linear scanning voltammetry(LSV) is instead utilized to attain a result of oxidation potential (or HOMO energy level) due to electrochemical oxidation of organic electroluminescent material filmed on the working electrode. In this electrochemical system, the supporting electrolyte tetrabutyl ammonium perchlorate (TBAP) synthesized by ourselves is dissolved in CHCl3 as well as CH2Cl2. It showed that the results may be better in CH2Cl2 than that in CHCl3 according to linear scanning voltammograms of Alq3 in 0.1mol·L-1 TBAP. It can be calculated that the HOMO energy level of Alq3 is 5.79eV from oxidation potential of linear scanning voltammogram of its film on the working electrode in 0.1 mol·L-1 TBAP(CH2Cl2), which is in good agreement with the result determined by other methods. We also have got the HOMO energy level of other electroluminescent materials, such as TPD, PBD, which is often acted as hole transporting material and electron transporting material. Their HOMO energy level is 5.44eV and 6.24eV, respectively. Then the LUMO energy levels calculated from their band gap are 3.0, 2.34, 2.94eV for Alq3, TPD, PBD. Less amounts of materials is consumed in this method. And the results showed that this method is faster and more convenient.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2003年第6期606-611,共6页
Chinese Journal of Luminescence
基金
国家自然科学基金重大研究计划(90201034)
国家自然科学基金(60077020)
上海市光科技专项(012261055)
国家"863"计划(2001AA313070)资助项目
