有机热活性型延迟荧光材料的分子设计

发布时间：2018-05-13 16:03

  本文选题：有机电致发光 + 热活性型延迟荧光　； 参考：《哈尔滨工业大学》2016年硕士论文

【摘要】：有机热活性型延迟荧光(Thermally Activated Delayed Fluorescence,TADF)材料可以在无贵金属的条件下实现100%的内量子效率,成为当前有机电致发光领域最活跃的研究热点之一。与荧光材料和磷光材料相比,有机TADF材料具有成本低、发光效率高等优点,被称为第三代电致发光材料。本论文设计了一系列具有TADF性质的有机分子,并基于密度泛函理论系统研究了其基态和激发态的几何构型,前线分子轨道,吸收、发射光谱,振子强度以及最低单重激发态-三重激发态能隙(ΔEST)等性质,从本质上揭示了分子结构与光物理性质之间的关系。主要研究内容如下:(一)以9-氢-噻吨-9-酮-10,10-二氧化物为受体(Acceptor,A),分别引入二苯胺、咔唑、9,9-二甲基-9,10-二氢吖啶、吩VA嗪四种不同的给体(Donor,D),以苯环(Ph)为连接桥,设计了D-A型、D-Ph-A型、D-A-D型、D-Ph-A-Ph-D型共16种噻吨酮类衍生物分子。基于最优Hartree-Fock交换方法预测了其TADF性质,深入研究了不同给体、Ph桥、双给体对TADF性质的影响。结果表明:对于D-A型分子,给体的空间位阻是影响ΔEST的决定性因素,空间位阻越大,ΔEST越小;引入Ph桥虽能够减小HOMO和LUMO重叠,但并不一定能够减小ΔEST,而引入双给体则对ΔEST几乎没影响。计算发现有7种分子ΔEST较小,同时具备一定的最优垂直吸收和发射振子强度(fVA(OHF)和fVE(OHF)),可能具有高效的TADF性质。本工作设计的一种分子(1d分子)的发射波长和ΔEST几乎与实验中的一种高效黄光TADF分子(1b分子)完全一致,但1d分子的fVA(OHF)和fVE(OHF)明显强于1b分子(分别增加了0.0323和0.0168),表明1d分子可能是一种更为高效的黄光TADF分子。(二)以N3,N3,N6,N6-四苯基-9-(4-(喹喔啉-6-基)苯基)-9H-咔唑-3,6-二胺分子(DACQ)为母体,通过引入不同给、吸电子取代基以及改变给、受体连接位置设计了8种喹喔啉类衍生物分子。基于同样的方法预测了其TADF性质,深入研究了取代基以及给、受体连接位置对TADF性质的影响。结果表明:在DACQ的受体上引入给电子取代基(-OCH3、-CH3)以及改变给、受体的连接位置,并不能降低ΔEST,但引入吸电子取代基(-2F、-4F与-CN),则可明显减小ΔEST,且分子的吸收和发射波长明显红移。其中分子7的发射波长为590 nm,fVA(OHF)和fVE(OHF)分别为0.1737和0.0954,ΔEST为0.093 eV。较小的ΔEST和较大的振子强度表明该分子可能是一种高效的黄光TADF分子。分子8和9的发射波长分别为660和680 nm,ΔEST分别为0.096和0.092 eV,两者都为红光TADF分子。与分子8相比,分子9具有更高的fVA(OHF)和fVE(OHF)(分别为0.2231和0.1061),表明分子9可能是一种更为高效的红光TADF分子。
[Abstract]:Thermally Activated Delayed delay fluorescence (TADF) materials with organic thermal activity can achieve an internal quantum efficiency of 100% without precious metals, which has become one of the most active research topics in the field of electroluminescence. Compared with fluorescent and phosphorescent materials, organic TADF materials have the advantages of low cost and high luminescence efficiency, so they are called the third generation electroluminescent materials. In this paper, a series of organic molecules with TADF properties are designed, and the geometric configurations of ground and excited states, frontier molecular orbitals, absorption and emission spectra are systematically studied based on density functional theory. The properties of oscillator strength and the lowest singlet excited triple-excited state gap (螖 EST) reveal the relationship between molecular structure and photophysical properties in essence. The main contents of this study are as follows: (1) four different donors, Donor Dy, were introduced as follows: (1) four different donor DonorDwith benzene ring Phi, respectively, diphenylamine, carbazolium 9-dimethyl-9-dimethyl-10-dihydroacridine, phenylethoxazine and phenylephrine, with 9H-thio-ton-9-keto-10- (10-) -dioxide as the acceptor. A total of 16 kinds of thiadione derivatives were designed for D-A and D-Ph-A, D-A-D and D-Ph-A-Ph-D, respectively. Based on the optimal Hartree-Fock exchange method, the TADF properties are predicted, and the effects of different donor Ph bridges and double donors on the TADF properties are studied. The results show that for D-A molecule, the steric resistance of donor is the decisive factor affecting 螖 EST, the larger the steric resistance is, the smaller the 螖 EST is, while the introduction of Ph bridge can reduce the overlap between HOMO and LUMO. However, 螖 ests are not necessarily reduced, and the introduction of double donors has little effect on 螖 EST. It is found that there are 7 molecules with small 螖 EST, and some optimal vertical absorption and emission oscillator intensities (fVAHV) and fVEOHF (OHF), which may have high TADF properties. The emission wavelengths and 螖 EST of a molecular molecule (1 d) designed in this work are almost identical to that of a highly efficient yellow light TADF molecule (1 b). However, the fVAHV) and fVEOHF of 1d molecule were significantly stronger than that of 1b molecule (0.0323 and 0.0168), respectively, indicating that 1d molecule might be a more efficient yellow light TADF molecule. (2) with N _ 3N _ 3N _ 3N _ 6N _ 6N _ 6- tetraphenyl -9-Or (quinoxaline -6-yl) phenyl--9H-carbazole-6-diamine molecule as the parent, eight derivatives of quinoxaline derivatives were designed by introducing different electron substituents and changing the acceptor sites. Based on the same method, the properties of TADF are predicted, and the effects of substituents and sites of acceptor junctions on the properties of TADF are studied. The results show that the insertion of electron substituent (OCH _ 3H _ 3H _ 3) and the change of the acceptor position can not decrease 螖 estr, but the absorption and emission wavelengths of the molecule are obviously red-shifted when the electron absorbing group is introduced into the acceptor of DACQ, and the absorption and emission wavelengths of the molecule are obviously red-shifted, if the electron absorbent group is introduced into the acceptor and the electron absorbing group is substituted by the electron acceptor -2F _ (-4F) and -CNN _ (+). The emission wavelengths of molecule 7 are 0.1737 and 0.0954, respectively, and the 螖 EST is 0.093 EV. The smaller 螖 EST and larger oscillator strength indicate that the molecule may be a highly efficient yellow light TADF molecule. The emission wavelengths of molecule 8 and 9 are 660 and 680nm, respectively, and 螖 EST are 0.096 and 0.092 EV, respectively. Both of them are red light TADF molecules. Compared with molecule 8, molecule 9 has higher fVAHv) and fVEOHFH (0.2231 and 0.1061g, respectively), indicating that molecule 9 may be a more efficient red light TADF molecule.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN383.1
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本文编号：1883871