稀土Sm掺杂八羟基喹啉类有机小分子薄膜的特性研究

发布时间：2018-05-03 06:24

本文选题：有机自旋电子学 + 有机半导体　；参考：《山东大学》2017年硕士论文

【摘要】：随着消费电子领域向轻、薄、大面积、柔性可折叠、节能环保、生物兼容、可穿戴等方向发展,有机半导体材料与器件研究受到世界各主要国家的重视,成为半导体及电子领域的热门前沿方向之一。有机半导体因其主要由轻元素组成,自旋轨道耦合相互作用及超精细相互作用弱,因此具有极长的自旋弛豫时间,是一类极有前景的自旋电子材料,有望先于无机半导体实现速度更快、超低功耗、数据非挥发的多功能新型自旋器件。新世纪以来,基于有机半导体的自旋电子器件如有机自旋阀、有机自旋发光二极管、有机磁性隧道结等先后研制成功,显示了有机半导体材料在自旋电子领域的光明前景。然而,由于自旋极化电极与有机层的匹配等问题的存在,目前有机自旋器件只在低温下具有较好的性能,在室温下的性能不高。开发具有铁磁性的有机半导体材料,作为自旋注入电极层或缓冲层材料,有望解决电导率不匹配造成的自旋注入效率问题,进而提高自旋电子器件及自旋光电子器件的室温性能。在本论文中,我们选取具有优异光电性质的八羟基喹啉类有机小分子材料和稀土钐金属元素,利用真空热蒸发方法制备了两种稀土掺杂八羟基喹啉有机小分子材料;测试表征了其形貌结构,并分析了稀土元素与有机分子的结合情况及电荷转移情况;测试了样品的磁性,分析了其磁性机理,获得了具有室温铁磁性的有机小分子材料,为研制基于该磁性材料的有机自旋电子器件及光电子器件提供了材料基础;测试了样品的光学性质,研究了稀土掺杂对样品光学性质的影响,获得了同时具有铁磁性、半导体导电性和优异光电性质的多功能有机材料,为研发集电子学、光学及磁学于一体的多功能及多场调控新型自旋器件提供了材料基础。主要研究内容和结果如下:一、稀土 Sm掺杂八轻基喹啉镓(Gaq_3)的制备、结构、磁性及光电性质研究。使用真空共蒸发方法首次制备了一系列不同掺杂浓度的稀土 Sm掺杂Gaq_3薄膜,并在样品中观察到了室温铁磁性,最大矫顽力为103.32 Oe,饱和磁化强度为4.1 x 10-6emu。通过分析磁性随Sm掺杂浓度的变化发现,样品的饱和磁化强度和矫顽力随着掺杂浓度的增大而增大,在名义掺杂浓度为15 wt.%时达到最大值,继续增大Sm浓度则样品磁性降低。我们对掺杂薄膜进行了结构分析,观察了掺杂薄膜的表面形貌,排除了金属Sm团簇的因素;分析FTIR图谱得出了掺杂之后分子结构并未出现明显的变化,说明掺杂金属Sm并未改变Gaq_3的结构,进而通过分析XPS图谱得出金属Sm原子作为施主原子有电子转移至Gaq_3分子,影响了 Gaq_3分子中N-Ga键,形成了两个新的峰位。然后,我们研究了掺杂薄膜的光电性质,通过对吸收光谱的测试,得到了在掺杂浓度为15wt.%时掺杂薄膜的禁带宽度出现了明显的变宽,可以理解为金属Sm原子向吡啶环上转移了电子,导致HOMO和LUMO之间能带变宽,我们还研究了掺杂薄膜的光致发光性质,发现在低掺杂浓度时有轻微的蓝移现象,在重掺杂时出现了明显的红色荧光峰位,说明掺杂的金属Sm影响了系统间的穿越常数(Kisc)。我们还研究了退火对Sm掺杂Gaq_3薄膜的影响。二、金属Sm掺杂八羟基喹啉锰(Mnq_2)的制备、结构及磁性研究。选用室温顺磁性稀土金属钐(Sm),和顺磁性的Mnq_2有机小分子,利用真空共蒸发方法首次制备了稀土 Sm掺杂的Mnq_2薄膜材料。原子力显微镜AFM研究显示当稀土金属Sm的质量比为7 wt.%时,掺杂薄膜均方根粗糙度为1.9 nm,与纯净的Mnq_2薄膜起伏相近,显示Sm掺杂对Mnq_2表面影响不大。交变梯度磁强计(AGM)室温磁性测试表明,经过稀土掺杂后样品呈现室温铁磁性,其磁性在Mn:Sm原子比为5.8:1时最强,矫顽力约为103.6 Oe,饱和磁化强度约为5.07 x 10-6emu。由于蒸发技术的限制,我们没有办法获得Sm掺杂比例比Mn:Sm=5.8:l更低的样品。随着Sm金属掺杂比例的提高,样品的磁性降低,当Mn:Sm原子比为1:1时,样品的饱和磁化强度降低至0.35x 10-6 emu。我们还研究了金属Dy掺杂八羟基喹啉锰(Mnq_2)的室温铁磁性,发现此体系的掺杂不会出现铁磁信号。
[Abstract]:As the field of consumer electronics is light, thin, large, flexible, folding, energy saving, environmental protection, biocompatibility, and wearable development, the research of organic semiconductor materials and devices has been paid much attention by the major countries in the world. It has become one of the hot frontiers in the field of semiconductors and electronics. Organic semiconductors are mainly composed of light elements and spin tracks. The channel coupling interaction and the hyperfine interaction are weak, so it has a very long spin relaxation time, which is a very promising kind of spintronic material. It is expected to achieve faster, ultra low power and nonvolatile multi-function spin devices than inorganic semiconductors. Since Neocene, the spintronic devices based on organic semiconductors, such as Organic spin valves, organic spin light-emitting diodes, and organic magnetic tunneling junctions have been developed successively. It shows the bright future of organic semiconductor materials in the field of spintronics. However, due to the existence of the matching of spin polarized electrode and organic layer, organic spin devices have good performance at low temperature at present, and at room temperature. The development of a ferromagnetic organic semiconductor material, as a spin injection electrode or a buffer layer material, is expected to solve the problem of spin injection efficiency caused by the mismatch of electrical conductivity, and then improve the room temperature performance of spintronic devices and spin optoelectronic devices. In this paper, we choose to have excellent photoelectric properties. Eight hydroxyquinoline organic small molecular materials and rare earth samarium metal elements were prepared by vacuum thermal evaporation method. Two kinds of rare earth doped eight hydroxyquinoline organic small molecular materials were prepared. Their morphology and structure were characterized. The combination of rare earth elements with organic molecules and charge transfer conditions were analyzed. The magnetic properties of the samples were tested and analyzed. The magnetic mechanism, obtained the organic small molecular material with room temperature and ferromagnetism, provided the material basis for the development of the organic spintronic devices and optoelectronic devices based on the magnetic material, tested the optical properties of the samples, studied the influence of the rare earth doping on the optical properties of the samples, and obtained the ferromagnetism and the conductivity of the semiconductor simultaneously. Multi-functional organic materials with excellent photoelectric properties provide a material basis for the development of a multifunction and multi field spin device for the integration of electronics, optics and magnetism. The main contents and results are as follows: first, the preparation, structure, magnetic and photoelectric properties of rare earth Sm doped eight light base quinoline gallium (Gaq_3). A series of rare earth Sm doped Gaq_3 films with different doping concentrations were prepared for the first time. The magnetic properties of room temperature and ferromagnetism were observed in the samples. The maximum coercive force was 103.32 Oe and the saturation magnetization was 4.1 x 10-6emu.. The saturation magnetization and coercivity of the samples were found with the doping concentration of Sm, and the saturation magnetization and coercivity of the samples were with the doping concentration. When the nominal doping concentration is 15 wt.%, the maximum value is reached and the Sm concentration continues to increase, and the magnetic properties of the samples are reduced. We have analyzed the structure of the doped thin film, observed the surface morphology of the doped thin film and excluded the factors of the metal Sm cluster, and the FTIR map showed that the molecular structure did not appear obvious changes after doping. It shows that the doped metal Sm does not change the structure of the Gaq_3, and then through the analysis of the XPS map, the metal Sm atom is transferred to the Gaq_3 molecule as the donor atom, which affects the N-Ga bond in the Gaq_3 molecule and forms two new peaks. Then, we have studied the photoelectrical properties of the doped thin films, and obtained the results by testing the absorption spectra. When the doping concentration is 15wt.%, the band gap of the doped film broadens obviously. It can be understood that the metal Sm atoms transfer electrons to the pyridine ring, which leads to the band widening between HOMO and LUMO. We also studied the photoluminescence properties of the doped thin films. The obvious red fluorescence peaks indicate that the doped metal Sm affects the crossing constant of the system (Kisc). We also studied the effect of Annealing on Sm doped Gaq_3 films. Two, the preparation, structure and magnetic properties of Sm doped eight hydroxyquinoline manganese (Mnq_2). The Mnq_2 thin film materials doped with rare earth Sm were prepared by vacuum co evaporation method for the first time. The atomic force microscope (AFM) AFM study showed that when the mass ratio of rare earth metal Sm was 7 wt.%, the RMS roughness of the doped thin film was 1.9 nm, similar to the pure Mnq_2 film, showing that Sm doping had little influence on the Mnq_2 surface. ) the room temperature magnetic test shows that the sample exhibits room temperature ferromagnetism after rare earth doping, and its magnetic properties are the strongest when the Mn:Sm atom ratio is 5.8:1, the coercive force is about 103.6 Oe and the saturation magnetization is about 5.07 x 10-6emu.. Because of the limitation of evaporation technology, we have no way to obtain the samples with Sm doping ratio lower than Mn:Sm=5.8:l. With the doping of Sm metal. When the ratio is increased, the magnetic properties of the sample are reduced. When the Mn:Sm atom ratio is 1:1, the saturation magnetization of the sample is reduced to 0.35x 10-6 emu.. We also study the room temperature ferromagnetism of the metal Dy doped eight hydroxy quinoline manganese (Mnq_2). It is found that the doping of this system does not show the ferromagnetic signal.

【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.2;O627.3

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