【作者】 张红；

【导师】 黎敏； 李伟；

【作者基本信息】 华中科技大学 ， 光学， 2019， 硕士

【摘要】 杂化有机-无机钙钛矿（Hybrid Organic-Inorganic Perovskites,简称HOIPs）作为一类“明星”材料凭借制备简单、带隙可调、化学组成多样等众多优异性能,近年来得到了光伏和光电子领域研究者的极大关注。HOIPs结合了有机材料和无机材料的众多优点,因此能表现出丰富的物理性质,在光伏、介电、磁性、铁电、铁弹、多铁等多方面具有广阔的应用前景。材料在工业加工过程中会受到各种应力的作用,如压缩、剪切、拉伸、弯曲、扭转、冲击、静水压等,HOIPs的力学性质对其未来工业化具有决定作用但相关研究却较少,因此充分掌握HOIPs材料的力学性能是确保其规模化应用的重要前提。此外,HOIPs材料在光伏和光电子领域的突出表现,使得对其基本结构-性能关系的研究显得尤为重要。Ruddlesden-Popper型钙钛矿（简称RPPs）作为一类结构高度可调的二维层状钙钛矿,引起了研究人员的广泛关注。随着无机层的厚度的改变,其光电性质也发生显著变化。本文选取几种具有代表性的HOIPs材料,通过多种表征手段以及第一性原理计算,结合理论和实验研究了力学性质,同时也对RPPs可调控光学性质进行了探究。主要内容如下:（1）利用溶液法合成了两种新的HOIPs材料:C₆H₁₄N₂·KBr₃和C₆H₁₄N₂·RbBr₃。利用单晶衍射、热重分析、红外光谱、元素分析等基本表征技术对其进行了综合的物相分析。结合第一性原理计算和纳米压痕实验,对两种材料的杨氏模量（E）、硬度（H）、剪切模量（G）、泊松比（ν）、体模量（B）以及各向异性指数（A）做了综合分析。结果表明与著名光伏材料CH₃NH₃PbI₃相比,C₆H₁₄N₂·KBr₃和C₆H₁₄N₂·RbBr₃具有更高的刚度和热稳定性。此外,结合弹性矩阵得到声速在晶体中的传播规律,进一步分析了晶体中纵波的振动和特性。（2）系统研究了三种不同n值的RPPs:（RNH₃）₂Cs_n-Pb_nBr_3n+1（n=1,2,∞）的晶体结构和光学性质。利用紫外可见吸收光谱测试、光致发光光谱（荧光）以及时间分辨光谱（荧光寿命）测试,发现随着n值的增大,材料的带隙变小,荧光寿命变长。因为RPPs中无机钙钛矿层的厚度可以由合成过程中所用药品的化学计量比的控制来实现,所以可以通过简易的化学合成来精确调控材料的光电性质。更多还原

【Abstract】 In recent years,hybrid organic-inorganic perovskites（HOIPs）have emerged as a class of"star"materials,which are due to their diverse chemical compositions,tunable band gaps,as well as simple synthesis.By combining both the virtues of organic and inorganic materials,HOIPs have shown abundant physical properties and broad application prospects in the field of photovoltaics,dielectrics,magnets,ferroelectrics,ferroelastics and multiferroics.In any process of industrial manufacturing,materials have to experience various stress which include compression,shearing,tensile,bending,twisting,impacting and hydrostatic pressure,however,there are very few studies about the mechanical properties of HOIPs.Therefore,it is necessary to study the fundamental mechanical properties of HOIPs.In addition,the prominent performance of HOIPs in photovoltaic and optoelectronics makes it important to study their structure-property relationships.Ruddlesden-Popper Perovskites（RPPs）,a family of two-dimensional perovskites with adjustable structures,have widely attracted researchers’attention.With the change of thickness of the inorganic layer,their photoelectric properties can be significanly tuned.In this thesis,a family of representative HOIP materials were synthesized,and their mechanical properties were characterized through experiments and first-principle calculations.The adjustable optical properties of a family of RPPs were also investigated experimentally.The main contents are as follows:（1）Two new HOIPs materials,C₆H₁₄N₂·KBr₃ and C₆H₁₄N₂·RbBr₃,were synthesized by solution method.Single crystal X-ray diffraction,elemental analysis,infrared spectral,thermogravimetric analysis were used for characterizing these two materials.Combined with first-principles calculations and nanoindentation experiments,the Young’s moduli,hardnesses,Shear moduli,Poisson’s ratios,bulk moduli and anisotropy indice of the two materials were analyzed comprehensively.The results showed that,compared with CH₃NH₃PbI₃,C₆H₁₄N₂·KBr₃ and C₆H₁₄N₂·RbBr₃ have stronger mechanical and thermal stability.In addition,by analyzing the elastic constants,the propagation law of sound velocity in both crystals were studied,the vibrations and characteristics of longitudinal waves were also further studied.（2）The crystal structures and optical properties of three RPPs with different values of n:（RNH₃）₂Cs_n-1Pb_nBr_3n+1（n=1,2,∞）were studied systematically.The spectra of ultraviolet-visible absorption and photoluminescence showed that with the increase of n,the band gaps of（RNH₃）₂Cs_n-1Pb_nBr_3n+1 decrease while the emission lifetimes strengthen.The thickness of the inorganic layer in RPPs can be controlled by changing the ratio between the organic and inorganic components,which enable the fine-tuning of the photoelectric properties.更多还原