红荧烯分子单重态激子裂变的分子间距依赖关系的研究

发布时间：2018-03-15 07:08

本文选题：红荧烯　切入点：激子裂变　出处：《西南大学》2017年硕士论文　论文类型：学位论文

【摘要】：近些年,国内外越来越多的研究者开始对单重态激子分裂过程(简称激子裂变)进行研究,激子裂变已成为有机电子学中热门的研究领域。现阶段,对激子裂变的研究主要在有机光伏器件上,能发生激子裂变的有机材料可作为一种新型的敏化剂,能够大幅度提升有机光伏器件的量子效率。由于在单重态激子裂变过程中,有机材料吸收一个光子后被激发,产生一个具有高能量的S1态激子,该S1态激子与一个处于基态的分子相互作用可转换为一对具有低能量的T1态激子,这将提升有机光伏器件的量子效率。且T1态激子比S1态激子寿命要长,扩散范围广,有利于激子的拆分解离,这可进一步的提高光电转换效率。目前,已有研究表明所制的有机薄膜器件中量子效率已经超过100%,如果能够将能发生激子裂变的有机材料用在工业上,将会解决能源问题。但是,目前对激子裂变研究过程中还存在许多问题,对其过程研究不够深入。本文中主要选了三个拟解决的问题进行研究。(1)有机薄膜材料的瞬态衰减曲线的拟合问题。在对激子裂变过程的研究中,实验上研究者主要是通过对有机材料的瞬态衰减过程进行研究。在对光致发光瞬态衰减曲线拟合时,主要有两种方法:一种用耦合速率方程组,但是拟合曲线与实验曲线符合的不太好;另一种用方程式进行拟合,虽然拟合曲线与实验曲线符合的很好,但是方程式的物理意义不明确,我们实验组针对该问题对不同rubrene掺杂浓度的薄膜瞬态衰减过程进行研究。(2)不同掺杂浓度的有机薄膜器件激子裂变速率与分子间距之间的关系。实验通过对不同rubrene掺杂浓度的薄膜进行研究,由于rubrene掺杂浓度不同可使分子间距不同,通过对薄膜的瞬态衰减过程进行研究,可得出激子裂变的速率,进而可得出激子裂变速率与分子间距之间的关系。(3)激子裂变的机制问题。目前,对于激子裂变机制主要有两种不同的看法:一种看法认为其为“内转换”模型;另一种认为其为“双电子转移”模型。本文通过对激子裂变过程进行分析,对激子裂变机制进行了验证。在实验中,通过双源共蒸的方法将不同浓度的rubrene分子掺杂到主体材料中,制成有机薄膜器件。由于rubrene分子的掺杂浓度不同使得分子间距不同,结合实验测量的薄膜器件在稳态下的光致发光光谱及瞬态衰减曲线,对激子裂变过程进行分析。本文主要解决了上述的三个问题。各章节的主要内容如下:(1)第一章主要介绍了激子裂变的动力学过程,能发生激子裂变的几种常见材料。同时,还说明了激子裂变的机制的两种不同观点,阐述了现阶段激子裂变研究背景,需要解决的问题及发展前景。(2)第二章主要对有机薄膜器件的制备,样品的光致发光光谱及瞬态衰减曲线的测量做了介绍。在对基片进行镀膜时,我们采用分子束外延技术,在真空度约为10-5Pa条件下对样品进行蒸镀,并详细阐述了实验所用到的真空系统及监控系统的原理及操作。同时,还对光致发光光谱和瞬态衰减曲线的测量仪器做了简单的介绍。(3)第三章通过对Alq3:rubrene(x%)有机薄膜的光致发光及瞬态衰减过程进行测量,其中x取值从2%到50%。由薄膜器件的发光光谱图分析得出了有机薄膜器件发光均来自rubrene分子。还得出一组既能够使拟合曲线与实验曲线符合的很好,物理意义明确的速率方程组。且经过分析薄膜的瞬态衰减曲线,得出了激子裂变速率与分子间距之间的关系为指数下降规律。同时,由拟合的瞬态衰减曲线对激子裂变电子转移过程进行分析,验证了激子裂变的机制为“双电子转移”模型,这对于明确激子裂变机制有重要的意义。
[Abstract]:In recent years, more researchers start to the singlet exciton splitting process (the exciton fission of exciton fission) has become a hot research field in organic electronics. At this stage, the research on exciton fission mainly in organic photovoltaic devices, organic materials can occur exciton fission can be used as a model the sensitizing agent, can greatly enhance the quantum efficiency of organic photovoltaic devices. Due to the singlet exciton fission process, organic material after absorption of a photon is excited to produce a high energy of S1 exciton, the S1 exciton and a ground state molecular interaction can be converted into a pair of with low energy T1 excitons, which will enhance the quantum efficiency of organic photovoltaic devices. And the T1 exciton exciton lifetime longer than S1, the diffusion range, there are split beneficial to the exciton dissociation. This can be further provided The high photoelectric conversion efficiency. At present, studies have shown that the organic thin film device made in quantum efficiency is more than 100%, organic materials can occur if the exciton fission in industry, will solve the energy problem. However, the exciton fission research process also exists a lot of problems, the research is not deep enough this paper mainly selected. Three problems to be solved are studied. (1) the fitting problem of transient organic thin film materials. The attenuation curve of exciton fission process, the researchers mainly through transient organic material degradation process were studied. The photoluminescence decay curve when fitting, there are two main ways: one using the coupled rate equations, but the fitting curve and the experimental curve with the not so good; another with a fitting equation, while the fitting curve and the experimental curve With the good, but the physical meaning of the equation is not clear, our experimental group to solve the problem of transient films of different doping concentration of rubrene decay was studied. (2) the relationship between organic thin film devices exciton fission rate and the distance between molecules of different doping concentration. The experimental research through the thin film of rubrene doped. Because of different doping concentration of rubrene can make the distance between molecules, by transient on the film attenuation process was studied. The rate of exciton fission, and obtained the relationship between exciton fission rate and molecular distance. (3) mechanism of exciton fission. At present, the main mechanism for exciton fission has two different views: one view is that the "conversion" model; another is that the "double electron transfer" model. Based on the exciton fission process analysis of shock Sub fission mechanism was verified. In the experiment, the method of using dual source co evaporation with different concentrations of rubrene molecules doped into the main material, made of organic thin film devices. Due to the different doping concentration of rubrene molecules and the molecular spacing, combined with experimental film device under steady state photoluminescence spectroscopy and transient decay the curve of exciton fission process were analyzed. This paper mainly solves the above three problems. The main contents of each chapter are as follows: (1) the first chapter mainly introduces the dynamic process of exciton fission, several common materials can occur exciton fission. At the same time, also illustrates the two different views of the mechanism of exciton fission. The present exciton fission research background, problems and future development needs to be solved. (2) the second chapter of the organic thin film device preparation, photoluminescence spectroscopy and transient decay Curve measurement is introduced. The coating on the substrate, we used molecular beam epitaxy in vacuum is about 10-5Pa of the samples under the conditions of evaporation, and expounds the principle and operation of the vacuum system used by the experiment and monitoring system. At the same time, the photoluminescence spectrum measuring instruments and the transient decay curves were briefly introduced. (3) the third chapter based on the Alq3:rubrene (x%) organic thin film photoluminescence and transient decay were measured, the x value from 2% to 50%. by the luminescence spectra analysis of thin film devices have been obtained from the light emitting machine thin film devices are drawn rubrene molecules. A group can make the fitting curve and the experimental curve is in good agreement with the rate equations, a clear physical meaning. And after the transient analysis of film decay curve, obtained the relationship between exciton fission rate and molecular distance for finger The law of number decline is also analyzed. Meanwhile, the electron transfer process of exciton fission is analyzed by fitting the transient decay curve. The mechanism of exciton fission is verified to be a "double electron transfer" model, which is of great significance for defining exciton fission mechanism.

【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN304.5;TN305

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