氨基酸改性氧化石墨烯的制备及光电性能的研究

发布时间：2018-05-03 20:42

本文选题：氧化石墨烯 + 氨基酸　；参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：氧化石墨烯(GO)是石墨烯常见的一种衍生物。因为边缘有着大量的含氧官能团,譬如羧基、羟基、环氧基等,使得GO在水、乙醇等溶剂里分散性较好。石墨烯或者GO在光电器件上是较有前景的下一代透明导电薄膜。为了得到好的器件性能,电极与活性层要有较好的能级匹配,这样能够提高电子或者空穴的传输速率。然而,GO的功函数大约为5.3 eV,石墨烯的功函数大约为4.7 eV,它们不能与大多数的活性材料的分子能级匹配。所以,调控石墨烯或者GO的功函数对于将它应用在光电器件中应用具有重要的意义。在之前的报道中,氨基酸作为一种偶极子已经用来调控铟锡金属氧化物薄膜(ITO)的功函数,因为它的表面偶极子作用,应用在光电器件里已经取得了较好的性能。本文主要的研究内容是用一种温和环保的方法将氨基酸接枝在氧化石墨烯上,旨在改变它的功函数。主要内容如下:GO通过改良的Hummers方法制得,制备的GO与氯乙酸钠反应,使得GO边缘的羟基转变为羧基。羧基化的GO在65°C经过亚硫酰氯(SOCl_2)活化24 h,得到GOCl(酰氯化的氧化石墨烯)。然后GOCl与氨基酸在二甲基甲酰胺(DMF)中于90°C反应24 h,得到氨基酸改性后的氧化石墨烯(GO-AA)。GO或者GO-AA经过一系列的表征手段,表明氨基酸与GO以共价键的方式结合得到GO-AA。GO的功函数为5.3 eV,GO-AA的功函数被调控到大约为4.0~4.5 eV。然后,将制得的GO-AA与聚(3,4-乙烯二氧噻吩)-聚苯烯磺酸(PEDOT:PSS)复合,该复合物的功函数都低于4.5 eV。将该复合物的悬浮液悬涂制得大约为20nm厚的薄膜,该薄膜的透光率能达到85%以上,最高电导率能达到1749 S·cm-1。以ITO/GO-AA的薄膜为阴极制得有机太阳能电池,在相同的工艺条件下,ITO/GO-AA做阴极的器件的短路电流密度(JSC)、开路电压(VOC)、光电转换效率(PCE)和外量子效率(EQE)较空白对比的器件稍高,说明低功函数的GO-AA能够起到提高电子收集速率的作用。尤其是当以ITO/PEDOT:PSS+GO-Cys(半胱氨酸改性的氧化石墨烯)做阴极时制得有机光电探测器,最高探测率能达到5.7×10~(12) Jones,在-0.1 V的偏压下具有较快的响应速度。这些结果表明,改性的氨基酸将在有机、无机、杂化光电器件里用作透明导电薄膜具有光明的前途。
[Abstract]:Graphene oxide (GOO) is a common derivative of graphene. Because there are a lot of oxygen-containing functional groups on the edge, such as carboxyl group, hydroxyl group, epoxy group and so on, go has good dispersion in water, ethanol and other solvents. Graphene or go is a promising next generation transparent conductive film in optoelectronic devices. In order to obtain good device performance, the electrode and the active layer should have better energy level matching, which can improve the transmission rate of electrons or holes. However, the work functions of go and graphene are about 5.3 EV and 4.7 EV, respectively, which can not match the molecular energy levels of most active materials. Therefore, it is important to regulate the work function of graphene or go for its application in optoelectronic devices. In previous reports, amino acids have been used as a dipole to regulate the work function of indium tin oxide (ITO) thin films because of its surface dipole effect, which has been applied to optoelectronic devices with good performance. The main content of this paper is to graft amino acids onto graphene oxide by a mild environmental protection method in order to change its work function. The main contents are as follows: (1) the reaction of go with sodium chloroacetate was prepared by the modified Hummers method, and the hydroxyl group at the edge of go was transformed into carboxyl group. The carboxylated go was activated by sulfite chloride SOCl2 at 65 掳C for 24 h to obtain GOCl (acylchlorinated graphene oxide). Then GOCl reacted with amino acid at 90 掳C for 24 h to obtain GO-AAN. Go or GO-AA modified by amino acids. The results showed that the work function of GO-AA.GO was regulated to be about 4.0 ~ 4.5eV when the work function of GO-AA.GO was 5.3 EV / GO-AA by covalent bonding of amino acid and go. Then, the GO-AA and PEDOT: PSS were synthesized, and the work functions of the complexes were all less than 4.5 EV. The film with 20nm thickness was prepared by suspension coating of the composite. The transmittance of the film can reach more than 85% and the highest conductivity can reach 1749 S cm-1. Organic solar cells were prepared by using thin film of ITO/GO-AA as cathode. The short circuit current density, open circuit voltage, optoelectronic conversion efficiency and external quantum efficiency of the devices with ITO / GO-AA cathode were slightly higher than those of the blank ones under the same process conditions. It shows that the GO-AA of low power function can improve the rate of electron collection. Especially, when ITO/PEDOT:PSS GO-Cys-modified graphene oxide was used as cathode, the photodetector was prepared. The highest detectivity can reach 5.7 脳 10 ~ (-1) Jones, and the response speed is faster at -0.1 V bias voltage. These results indicate that the modified amino acids will be used as transparent conductive films in organic, inorganic and hybrid optoelectronic devices.
【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】：2015
【分类号】：TQ127.11

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