ZnqCl_2及其衍生物的电子光谱性质的含时密度泛函理论研究

TD-DFT Study on Electronic Spectrum Properties of ZnqCl_2 and Its Derivatives

采用从头算法(abinitio)和密度泛函理论(DFTB3LYP)方法,对二氯取代的八羟基喹啉锌(ZnqCl2)及其2种衍生物的基态结构进行优化,同时用abinitioHF单激发组态相互作用(CIS)法在6-31G(d)基组上优化其最低激发单重态几何结构,用含时密度泛函理论(TD-DFT/B3LYP)及6-31G(d)基组计算吸收和发射光谱。计算表明,该类物质电子在基态与激发态间的跃迁,主要是在配体8-羟基喹啉(q)环内的电荷转移,电子从含O的苯酚环转移至含N的吡啶环上,发射光谱的计算值与实验值基本符合。该类化合物的电子亲和能较大,都是优良的电子传输材料,改变中心金属原子对配合物光谱性质影响不大。

Organic/polymeric electroluminescence （EL） has attracted much attention because of their potential applications in larger-area full-color flat-panel displays. Since the first high efficient organic light emitting diode （OLED）, which used the aromatic diamine as the hole transport layer and tris （8-hydroxyquinoline） aluminum （Alq3） as the electron transport/emission layer, was demonstrated by C. W. Tang in 1987, Alq3 is commonly used as the electron transport and/or emitting layer in OLEDs for its high fluorescent efficiency, high crystallizing temperature and stable performance. Recently, in order to get higher devices, many efforts have been made on the synthesis of high luminescence efficient ZnqCl2 have been synthesized and also its light-emitting devices were prepared by P. Y. efficient and stable materials, such as Liu etc. Methods of calculation quantum chemistry are effective tools for studying the mechanism of photostimulated luminescence materials. To our knowledge, up to the present, there has not been any theoretical report on the spectrum of ZnqCl2. In this paper, two derivatives of ZnqCl2 （MqCl2, M = Mg, Be） are designed, and the struetures of gqCl2 （g = Zn, Mg, Be） and Znq2 were optimized in the ground states using ab irdtio HE and B3LYP methods. At the same time, the molecular structures of the first singlet excited state for.ZnqCl2 and its derivatives were optimized by CIS/6-31G（d）. The absorption and excite spectra based on the abovestructures were obtained by the time-dependent density functional theory （TD-DFT） by the B3LYP method with ther-31G（d） basis set. The calculated results of luminescence originate from the electronic transition from the hydroxphenol ring to the pyridine ring. The calculated results of emission spectrum for agreement with the experimental data. All compounds （MqCl2, M =Zn, Mg, Be） are excellent electrontransporting materials, the luminescence peak wavelength of them can be tuned little by,different metals on the ligand 8-hydroxyquinolinateo anion.