基于CdSe量子点电致发光器件性能的研究

发布时间：2018-06-30 07:26

本文选题：量子点 + 电致发光　；参考：《北京交通大学》2015年硕士论文

【摘要】：量子点是一种理想的荧光材料,它可以通过控制其尺寸来调节发射荧光的波长,并且具有宽的激发光谱、窄的发射光谱、高的荧光量子产率、长的荧光寿命、颜色可调和光化学稳定性高等特殊性质,这些性质使得半导体量子点在各种光电器件、生物标识、单电子器件、以及存贮器等方面具有极为广泛的应用。研究量子点电致发光器件,提高其性能具有十分重要的理论意义和应用价值。本论文以量子点器件的电致发光性能为研究对象,为了提高量子点器件的发光性能,采取了以下两种方法： (1)插入氧化钼(MoO3)层作为电荷生成层来提高量子点器件的发光；分别制备了基础器件和插入氧化钼层的双叠层量子点器件,通过测试得到了两组器件的发光,相对于基础器件而言,插入插入氧化钼(MoO3)层作为电荷生成层来提高量子点器件的发光是可行且有效的,使电流效率从2.1cd/A提高到3.3cd/A。并进一步优化器件的结构,利用阴极PFN和阳极PEDOT:PSS的修饰,使量子点器件的性能进一步提高,其电流效率达到了5.1cd/A。 (2)插入Ir (ppy)3:CBP层,将Ir (ppy)3作为有效的激子和能量给体,通过调整施主浓度和受体—给体的距离,使量子点器件的发光增强。制备了掺杂浓度5%-30%的器件,随着掺杂浓度的增加,量子点的发光先增强后减弱,且在低浓度下只观察到量子点发光,随着浓度的增加,Ir (ppy)3也开始发光。存在个合适的临界浓度15%使量子点的发光达到最佳值。同时还制备了掺杂厚度从8nm到35nm的一系列器件,发现Ir (ppy)3:CBP的临界厚度大约是在14nm到18nm,当厚度超过了这个临界厚度时,在Ir (ppy)3内形成的激子会发生辐射衰减。最后,本论文还研究了红、绿、蓝三种颜色的量子点混合器件电致发光的过程,混合器件是利用红、绿、蓝三种颜色的量子点按照1：1的比例两两混合,制备成结构为ITO/PEDOT:PSS/QDs/Al的器件。研究发现在一定电压范围内,单种量子点器件的发光强度随着电压增加持续上升,而混合量子点器件的发光出现了短波长下降,长波长上升的现象,表明当有外加电场时不同尺寸的量子点间产生了较高效率的能量转移。同时对混合量子点电致发光器件能量转移的各项参数进行了计算,得到了能量转移效率E、临界能量转移距离R0与外加电场的关系,对制备白光量子点电致发光器件具有指导意义。
[Abstract]:Quantum dots are an ideal fluorescent material, which can adjust the wavelength of emission fluorescence by controlling its size, and has wide excitation spectrum, narrow emission spectrum, high fluorescence quantum yield, long fluorescence lifetime. Color tunable photochemical stability and other special properties make semiconductor quantum dots have a wide range of applications in various optoelectronic devices biomarkers single electronic devices memory and so on. It is very important to study quantum dot electroluminescent devices and improve their performance. In this paper, the electroluminescent properties of quantum dot devices are studied, in order to improve the luminescence performance of quantum dots devices, The following two methods are adopted: (1) Molybdenum oxide (MoO _ 3) layer is inserted as the charge generation layer to improve the luminescence of quantum dot devices, and the basic devices and the double-layer quantum dot devices with molybdenum oxide layer are fabricated, respectively. Compared with the basic devices, it is feasible and effective to increase the luminescence of QDs by inserting molybdenum oxide (MoO3) layer as the charge generation layer, and the current efficiency is increased from 2.1cd/A to 3.3 cdr / A. Furthermore, the structure of the device was optimized, and the performance of QDs was further improved by the modification of cathode PFN and anode PEDOT: PSS. The current efficiency of QDs reached 5.1 cdr / A.2 (2) the ir (ppy) _ 3 was inserted into the ir (ppy) _ 3: CBP layer, and the ir (ppy) _ 3 was used as an effective exciton and energy donor. The luminescence of the QDs is enhanced by adjusting the donor concentration and the distance between the acceptor and the donor. With the increase of doping concentration, the luminescence of quantum dots was first enhanced and then weakened, and only the luminescence of quantum dots was observed at low concentration, and the luminescence of ir (ppy) _ 3 began with the increase of concentration. The existence of an appropriate critical concentration of 15% makes the luminescence of quantum dots optimal. At the same time, a series of devices with doping thickness from 8nm to 35nm have been fabricated. It is found that the critical thickness of ir (ppy) 3: CBP is about from 14nm to 18 nm. When the thickness exceeds this critical thickness, the exciton formed in ir (ppy) 3 attenuates. Finally, we study the electroluminescence process of the hybrid devices of red, green and blue. The hybrid devices are composed of red, green and blue quantum dots in a 1:1 scale. A device with the structure of ITO / PEDOT: PSS / QDs / Al was fabricated. It is found that in a certain voltage range, the luminescence intensity of a single quantum dot device increases continuously with the increase of voltage, while the luminescence of a hybrid quantum dot device decreases in short wavelength and rises in long wavelength. It is shown that when there is an external electric field, the energy transfer between quantum dots of different sizes is more efficient. At the same time, the energy transfer parameters of hybrid quantum dot electroluminescent devices are calculated. The energy transfer efficiency E, the critical energy transfer distance R 0 and the applied electric field are obtained. It can be used to fabricate white quantum dot electroluminescent devices.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O471.1;TN383.1

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