【作者】 王伟；

【导师】 王立；

【作者基本信息】 南昌大学 ， 材料科学与工程， 2021， 硕士

【摘要】 光电探测器是一种可以将光信号转换成电信号的器件,它在光通信、光谱学、环境监测、生物传感器领域有着广泛的应用。近年来,由于卤化铅钙钛矿具有吸收系数高,光吸收范围宽,载流子扩散长度长,载流子迁移率高以及可溶液加工等特点,被视为是下一代半导体材料。相比于传统的无机半导体材料,基于卤化铅钙钛矿的优点,可以制备出低成本、大面积、柔性、多功能的卤化铅钙钛矿光电探测器。在卤化铅钙钛矿众多的结构（单晶、薄膜、低维钙钛矿）中,一维卤化铅钙钛矿具有高的比表面和一维限域效应,是制备光电探测器的有利材料。但是高质量一维卤化铅钙钛矿不易制备,光生载流子容易在表面复合。因此高质量的一维卤化铅钙钛矿的高效合成,以及提高对载流子分离和传输的结构设计,对一维卤化铅钙钛矿探测器的应用发展具有非常重要的意义。本文介绍了一种新的一维有机-无机卤化铅钙钛矿微米线的合成方法,对微米线进行设计构建出了有利于载流子分离和传输的核壳异质结结构,并成功制备高性能的光电探测器,主要研究工作如下:1.一维（CH₃）₂C=NHCH₃PbBr₃卤化铅钙钛矿微米线的制备。CH₃NH₃PbBr₃卤化铅钙钛矿单晶与丙酮溶液反应,通过A位阳离子的反应诱导钙钛矿晶体相变,可以得到厘米级的（CH₃）₂C=NHCH₃PbBr₃卤化铅钙钛矿微米线,产率高达80%。研究证实,要与CH₃NH₃PbBr₃卤化铅钙钛矿单晶中的A位阳离子CH₃NH₃⁺发生反应,有机试剂除了要含有能与CH₃NH₃⁺反应的官能团外,有机试剂分子的尺寸也必须合适。单晶X射线衍射测试表明（CH₃）₂C=NHCH₃PbBr₃卤化铅钙钛矿微米线属于三方晶系,具有独特的面共享三棱柱晶体结构。2.一维（CH₃）₂C=NHCH₃PbBr₃/CH₃NH₃PbBr₃核壳异质结微米线的设计。通过研究发现,在有水存在的条件下,A位阳离子反应是可逆的。（CH₃）₂C=NHCH₃PbBr₃卤化铅钙钛矿微米线的表面会缓慢地转换成CH₃NH₃PbBr₃卤化铅钙钛矿单晶,从而形成表面是CH₃NH₃PbBr₃卤化铅钙钛矿层和内部是（CH₃）₂C=NHCH₃PbBr₃卤化铅钙钛矿层的（CH₃）₂C=NHCH₃PbBr₃/CH₃NH₃PbBr₃核壳异质结微米线。随着核壳异质结的形成,源自CH₃NH₃PbBr₃卤化铅钙钛矿的发光强度也增强。重塑的CH₃NH₃PbBr₃卤化铅钙钛矿不仅结晶质量较高,而且稳定,在空气中放置454天也不分解。这种具有高稳定的一维核壳异质结微米线,为卤化铅钙钛矿光电探测器的应用奠定了坚实的基础。3.一维（CH₃）₂C=NHCH₃PbBr₃/CH₃NH₃PbBr₃核壳异质结光电探测器的性能研究。在单根（CH₃）₂C=NHCH₃PbBr₃卤化铅钙钛矿微米线的两端分别滴上银浆作为光电探测器的电极,使电极的距离尽可能近,但不能形成短路。然后将其暴露在空气中,（CH₃）₂C=NHCH₃PbBr₃卤化铅钙钛矿微米线未被银浆覆盖的区域表层会转换成CH₃NH₃PbBr₃卤化铅钙钛矿,这样就得到了叉指型的（CH₃）₂C=NHCH₃PbBr₃/CH₃NH₃PbBr₃核壳异质结微米线光电探测器。对光电探测器进行测试发现,得益于异质结结构的存在能抑制了载流子的复合,增长了载流子寿命,有利于载流子的分离,在460nm的光激发下,（CH₃）₂C=NHCH₃PbBr₃/CH₃NH₃PbBr₃核壳异质结探测器具有较大的响应度(66.8mA W^-1),高响应速度（2.8ms/0.8ms）。更多还原

【Abstract】 Photodetector is a device that can convert optical signals into electrical signals,and has a wide range of applications in the fields of optical communications,spectroscopy,environmental monitoring,and biosensors.In recent years,lead halide perovskites have been regarded as next-generation semiconductor materials due to their high absorption coefficient,wide light absorption range,long carrier diffusion length,high carrier mobility,and solution processability.Compared with traditional inorganic semiconductor materials,based on the advantages of lead halide perovskites,low-cost,large-area,flexible,and multifunctional lead halide perovskites photodetectors can be prepared.Among the numerous structures of lead halide perovskite（single crystal,thin film,low-dimensional perovskite）,one-dimensional lead halide perovskite has a high specific surface area and one-dimensional confinement effect,and is a favorable material for the preparation of photodetectors.However,high-quality one-dimensional lead halide perovskites are not easy to prepare,and photo-generated carriers are easy to recombine on the surface.Therefore,the high-efficiency synthesis of high-quality one-dimensional lead halide perovskite and the structural design to improve carrier separation and transmission are of great significance to the application and development of one-dimensional lead halide perovskite detectors.In this dissertation,a new synthesis method of one-dimensional organic-inorganic lead halide perovskite microwires is introduced.The microwires are designed to construct a core-shell heterojunction structure that is conducive to carrier separation and transmission,and successfully prepared high-performance photodetector.The main research work is as follows:1.Preparation of one-dimensional（CH₃）₂C=NHCH₃PbBr₃ lead halide perovskite microwires.The CH₃NH₃PbBr₃ lead halide perovskite single crystal reacts with CH₃COCH₃.This reaction leads to the formation of centimeter-level（CH₃）₂C=NHCH₃PbBr₃ lead halide perovskite microwires through the A-site cation induce phase transformation,and the yield is as high as 80%.Studies have confirmed that in order to react with the A-site cation CH₃NH₃⁺in the CH₃NH₃PbBr₃ lead halide perovskite single crystal,the organic reagent must contain functional groups that can react with CH₃NH₃⁺,and the molecular size of the organic reagent must also be appropriate.Single crystal X-ray diffraction test shows that（CH₃）₂C=NHCH₃PbBr₃lead halide perovskite microwire belongs to the trigonal crystal system,with a unique face-sharing triangular prism crystal structure.2.The design of one-dimensional（CH₃）₂C=NHCH₃PbBr₃/CH₃NH₃PbBr₃core-shell heterojunction wirowires.Through research,it is found that in the presence of water,the A-site cation reaction is reversible,and the surface of the（CH₃）₂C=NHCH₃PbBr₃ lead halide perovskite microwire will slowly transform into CH₃NH₃PbBr₃ lead halide perovskite single crystal.Thereby forming a（CH₃）₂C=NHCH₃PbBr₃/CH₃NH₃PbBr₃ core-shell heterojunction wirowires with a CH₃NH₃PbBr₃ lead halide perovskite layer（surface）and a（CH₃）₂C=NHCH₃PbBr₃lead halide perovskite layer（inside）.With the formation of the core-shell heterojunction,the luminescence intensity derived from the CH₃NH₃PbBr₃ lead halide perovskite has also increased.The CH₃NH₃PbBr₃lead halide perovskite obtained by remolding is not only very high in crystal quality,but also stable,and does not decompose even if it is placed in the air for 454 days.This one-dimensional core-shell heterojunction microwire with high stability has laid a solid foundation for the application of lead halide perovskite photodetectors.3.Resaech on the performance of one-dimensional（CH₃）₂C=NHCH₃PbBr₃/CH₃NH₃PbBr₃core-shell heterojunction photodetector.Drop silver paste on both ends of a single（CH₃）₂C=NHCH₃PbBr₃lead halide perovskite microwire as the electrodes of the photodetector.The distance between the electrodes is as close as possible without forming a short circuit.Then expose it to the air,and the surface layer of the area where the（CH₃）₂C=NHCH₃PbBr₃ lead halide perovskite microwire is not covered by the silver paste will be converted into CH₃NH₃PbBr₃ lead halide perovskite,thus obtaining the interdigital（CH₃）₂C=NHCH₃PbBr₃/CH₃NH₃PbBr₃core-shell heterojunction microwire photodetector.The study found that benefiting from the existence of the heterojunction structure can inhibit the recombination of carriers and increase the carrier lifetime,and facilitate the separation of carriers.Under 460nm light excitation,the（CH₃）₂C=NHCH₃PbBr₃/CH₃NH₃PbBr₃ core-shell heterojunction photodetector has a large responsivity of 66.8 mA W^-1 and a high response speed（2.8ms/0.8ms）.更多还原