【作者】 张敏；

【导师】 赵武；

【作者基本信息】 西北大学 ， 电路与系统， 2018， 硕士

【摘要】 近几年来,一种最具潜力的新型光电材料—有机-无机金属卤化物钙钛矿材料的出现,使得人们的目光再次聚焦在光伏、发光器件、激光、传感器等多个领域。相比于传统的半导体材料,这种新型的半导体材料具有原料来源广,可溶液处理、合成简单、载流子迁移率高、带隙可调,可实现光谱调控等诸多优点。自2014年,剑桥大学Tan.et al首次实现以甲胺铅溴(MAPbBr3)作为主体发光材料在室温下发光以来,短短的几年时间内其钙钛矿发光二极管的性能大幅度提升。但是钙钛矿材料在电致发光器件研究领域中还存在诸多问题亟待解决,如改善钙钛矿薄膜的结晶形貌,减少漏电流,提高其稳定性等。本论文结合研究团队在有机电致发光器件研究基础之上,通过制备出高质量钙钛矿薄膜,从而提高钙钛矿发光二极管的亮度和效率,主要工作包括以下三个方面:1.采用一步旋涂工艺制备钙钛矿薄膜的基础上,向MAPbBr3钙钛矿前驱液中加入不同体积的苯乙胺溶液,通过分析苯乙胺溶液对MAPbBr3薄膜形成的形貌特征和晶体特性之间的关系,结合相应的器件性能测试结果,以此来探究苯乙胺溶液对MAPbBr3钙钛矿薄膜的性能并优化工艺,从而获得最大亮度29268 cd/m2和最高效率9.81 cd/A的钙钛矿发光二极管。2.研究不同添加剂,苯胺溴、苯甲胺溴和苯乙胺溴三种物质对钙钛矿薄膜形貌和器件性能的影响,揭示添加不同链长的苯基烷胺溴对最终钙钛矿发光二极管性能的影响规律。研究发现当没有二维材料的添加时,MAPbBr3形成的薄膜颗粒较大,覆盖率较低,荧光强度和荧光寿命较差。当在MAPb Br3中引入过量的苯胺溴,苯甲胺溴或者苯乙胺溴,薄膜覆盖率达到100%,随着二维材料含量的不断增大,苯胺溴对钙钛矿薄膜的影响变化最大,薄膜覆盖率急剧下降,颗粒明显变大,苯甲胺次之,苯乙胺溴变化较小,薄膜覆盖率较高,从而可以得出,链长越长,对MAPbBr3影响越大,薄膜颗粒越小,覆盖率越低。链长越长对发光二极管的传输性能越差,从而导致发光二极管的性能较差,但是链长越长发光二极管的稳定性越好。反之链长越短,发光二极管的传输性越好,但是当MAPbBr3中含量稍微减少的时候,薄膜的覆盖率急剧下降,导致发光二极管的漏电流较大,从而使得发光二极管的性能变差,发光二极管的稳定性越差。3.空气中制备全无及钙钛矿(CsPbBr3)薄膜,通过改变CsBr,PbBr2的比例调控晶体结构,当CsBr的添加未过量的时候,CsPbBr3薄膜的晶体结晶性很差,并且存在枝状晶体生长,同时也会导致薄膜覆盖率很差;随着CsBr添加的比例逐渐提高到,CsPbBr3薄膜晶体结晶性越来越好,颗粒明显减小,薄膜覆盖率明显提高,生长被适量的CsBr所抑制,从初始的枝状晶体转化为立方状晶体。此外,当CsBr在薄膜中过量的时候,会形成不同的晶体结构,从而导致薄膜的荧光强度很强,器件的性能大幅度提升,最终得到4.6cd/A的效率和43686cd/m2的亮度的高性能发光二极管。更多还原

【Abstract】 Over the past few years,the appearance of an organic-inorganic metal halide perovskite material makes people’s attention focused on photovoltaics,light emitting devices,lasers,and sensors.Compared with traditional semiconductor materials,this new type of semiconductor material has many advantages such as wide source of raw materials,simple solution processing,simple synthesis,high carrier mobility,adjustable band gap,and spectrum control.Since 2014,Tan from Cambridge University realized methylamine lead bromine(MAPbBr3)as the main luminescent material emits light at room temperature for the first time.The performance of its perovskite light-emitting diodes has greatly improved in short period of several years.However,perovskite materials still have many problems in the field of electroluminescent devices,such as improving the crystal morphology of perovskite films,reducing leakage current,and improving their stability.Based on the research of organic electroluminescence devices,this paper prepared high-quality perovskite films in the use of perovskite light-emitting diodes which improve the brightness and efficiency.The main work includes the following three aspects:1.Based on the one-step spin-coating process for the preparation of perovskite films,different volumes of phenylethylamine solution were added to the precursor of MAPb Br3 perovskite.We analyzed the relationship between the morphology of the MAPbBr3 film formed by the phenethylamine solution and crystal characteristics,combined with the corresponding device performance test results,to explore the performance of phenethylamine solution on MAPb Br3 perovskite film and optimize the prepare process.Finally we obtained the maximum brightness 29268 cd/m2 and the highest efficiency of 9.81 cd/A of perovskite light-emitting diodes.2.We studied the effects of different additives on the morphology and device performance of perovskite films,such as aniline bromide,benzylamine bromide,and phenylethylamine bromide.These researches revealed the law of performance,which is adding phenylalkylamine bromide with different chain lengths to the final perovskite light-emitting diode.It was found that if the two-dimensional material was not added,the MAPbBr3 would form larger film particles,lower coverage,poor fluorescence intensity and fluorescence lifetime.When excessive amount of aniline bromide,benzylamine bromide or phenylethylamine bromide was introduced into MAPbBr3,the film coverage reaches 100%.With the continuous increase of the content of two-dimensional material,aniline bromide influence the perovskite film greatest.The film coverage rate sharply decreased and particles became larger.Phenethylamine bromide had little change,and the film coverage was still high.It can be concluded that the longer chain length,the greater impact on MAPbBr3.The longer chain length,the transmission performance of the light emitting diode is more poor,resulting in poor performance of the light emitting diode.But the stability of the light emitting diode is better.Conversely,the shorter chain length,the light-emitting diode transmission become better.But when the content of MAPbBr3 slightly reduced,the coverage of the film is drastically reduced,resulting in a larger leakage current of the perovskite light-emitting diode,which deteriorates the performance and stability of the perovskite light-emitting diode.3.The preparation of perovskite-free and perovskite(CsPbBr3)thin films in the air,and by adjusting the proportion of CsBr,PbBr2 to regulate the crystal structure.the study found that when the addition of CsBr is not excessive,the crystallinity of the CsPbBr3 thin film is poor,and the presence of dendritic crystal growth,At the same time,it also results in poor film coverage.As the proportion of CsBr addition gradually increases,the crystallinity of the CsPbBr3 thin film becomes better and better,the particles decrease obviously,the coverage of the thin film increases remarkably,the growth is inhibited by appropriate amount of CsBr,and the conversion from the initial dendrite into Cubic crystals.In addition,when CsBr is excessive in the thin film,different crystal structures are formed,resulting in a strong fluorescence intensity of the thin film,and the performance of the device is greatly improved.Finally,we obtained a high-performance perovskite light-emitting diodes with an efficiency of 4.6 cd/A and brightness of 43686 cd/m2.更多还原