具鈣鈦礦結構材料之光學特性

Optical properties of perovskite

魏子喬(Tzu-Chiao Wei)

指導教授 ： 林恭如

國立臺灣大學/電機資訊學院/光電工程學研究所/博士(2017年)

https://doi.org/10.6342/NTU201700878

摘要

在本論文中，我們分析了具有鈣鈦礦結構材料之光至伸縮特性，包括過度金屬氧化物釕酸鍶(SrRuO3，簡稱SRO)與有機無機混和鈣鈦礦甲基氨基溴化鉛(Methylammonium Lead Bromide，CH3NH3PbBr3，簡稱MAPbBr3)。
具有鈣鈦礦結構之材料通常具有較強的電荷、電子自旋與晶格自由度的關聯耦合，透過對於材料之拉曼光譜量測與分析，藉由聲子頻率隨激發光源強度之變化，可觀察到材料結構在應力上的改變。在單晶釕酸鍶薄膜中，我們觀察到了1.12%的應力變化，其可歸應於材料晶體與激發光子造成的聲子非平衡現象。對於單晶鈣鈦礦甲基氨基溴化鉛，其光至伸縮係數在可見光下可高達.08 × 10-8 m2 W-1，其物理原因乃材料具強烈的平移與旋轉耦合特性與光伏效應和分子構型的平移對稱性損失。除此之外，我們亦研究單晶鈣鈦礦甲基氨基溴化鉛之非線性光學特性及其應用，包括光頻譜之整形、穩定及限幅。結果顯示具有鈣鈦礦結構之材料在相關光學領域具有許多應用之潛能。

關鍵字

光致伸縮 ； 釕酸鍶 ； 鈣鈦礦 ； 非線性光學

並列摘要

In this thesis, we have investigated the photostrictive effect of the transition metal oxide strontium ruthenate (SrRuO3, SRO) with perovskite structure and organic-inorganic hybrid perovskite CH3NH3PbBr3 (MAPbBr3) using Raman spectroscopy.
Materials with a perovskite crystal structure usually displays unusually strong coupling of charge, spin and lattice degrees of freedom, which can give rise to the photostriction, In Raman scattering measurements, the phonon mode of the perovskite materials showed a shift with laser intensity, indicating the changes in the physical dimensions of material due to the absorption of light illumination. We observe a photon-induced strain as high as 1.12% in single domain SRO, which we attribute to a non-equilibrium of phonons that are a result of the strong interaction between the material’s crystalline lattice and electrons excited by light. For single crystal perovskite MAPbBr3, we were able to calculate the photostrictive coefficient as high as 2.08 × 10-8 m2 W-1 at room temperature under visible light illumination. We attribute the significant photostriction to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation-rotation coupling. Moreover, we have demonstrated several nonlinear optical applications of MAPbBr3, including optical reshaping, stabilization, and limiting behavior on intense pulsed laser signals, opening new applications for perovskites in the field of photonics.

並列關鍵字

photostriction ； SRO ； perovskite ； nonlinear optical

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