高分子/鈣鈦礦複合材料：奈米粒子生長, 結構分析和電子以及光電應用

Polymer/Perovskite Composites: Nanoparticle Growth, Morphology Analysis, Electronic and Optoelectronic Applications

徐安達(Ender Ercan)

指導教授 ： 陳文章

國立臺灣大學/工學院/化學工程學研究所/博士(2019年)

https://doi.org/10.6342/NTU201903757

摘要

近年來，有機-無機雜化鈣鈦礦（OIHP）材料有著優異的電學及光學性質，因此引起各大學者對該材料的研究熱忱。雖然材料本身具有這樣優異的特性，但是在元件的機械性質及穩定性上，仍有許多重大的限制及挑戰。為了克服這些缺點，其中最常採用的方法之一是形成鈣鈦礦/聚合物複合材料，進而保有鈣鈦礦及高分子材料的優點。在本論文中，我們著重於探討OIHP的奈米粒子的形成以及其與高分子之間的化學作用力，除此之外，探討這種複合材料的優勢以及相關光電元件的應用，如記憶裝置和發光元件，每個主題的細節總結如下。
於本論文第二章，我們將OIHP材料 (CH3NH3PbBr3)奈米顆粒分散在絕緣固體聚合物電解質（poly(ethylene oxide) (PEO)）中。由於Pb2+陽離子與PEO鏈上的醚氧電子對之間的相互作用，PEO可作為螯合劑與PbBr2/CH3NH3PbBr3奈米顆粒作配位，為Pb2+陽離子提供主體介質形成晶相與非晶相。選擇PEO不僅是因為其離子電導率而發揮基質功能，且因為還能支持CH3NH3PbBr3奈米顆粒周圍的防腐材料，以提高其穩定性。因此，我們提出其是穩定的低電阻狀態的起點和反向偏壓掃描期間導電路徑的恢復。這項研究提出了基於鈣鈦礦的電阻式記憶元件的新視角。
於本論文第三章中，我們進一步探討了聚合物基質對以鈣鈦礦材料應用的光誘導型記憶元件之光響應和記憶特性的影響。於本論文中研究了四種不同的主體聚合物，分別為聚苯乙烯（PS），聚（4-乙烯基苯酚）（PVPh），聚（甲基丙烯酸甲酯）（PMMA）和聚（甲基丙烯酸）（PMAA）。由於不同尺寸分佈的鈣鈦礦奈米顆粒以及混合介電層的不同形貌使得主體聚合物和鈣鈦礦材料之間有著不同的化學交互作用力。以不同的聚合物與鈣鈦礦材料所組成的材料所做成的光誘導型記憶元件有因此有著不同的記憶行為。
於本論文第四章中，我們使用殼核電紡絲法來形成OIHP奈米粒子/熱塑性聚氨酯（polyurethane, TPU）的奈米纖維。由於OIHP與TPU之間的化學親和力，奈米粒子保存得很好，而其粒徑分布則是由溶液參數以及操作參數來控制。而不同顏色的OIHP奈米纖維則是藉由改變OIHP前驅物的組成來做控制。製備出的核殼奈米纖維由於TPU的良好彈性性質而表現出高機械耐久性，並且在100次拉伸-鬆弛循環後，即使在100％拉伸狀態下也保持發光強度，利用TPU的疏水性所製成的纖維對於環境及濕度穩定性也提高了一個月的耐久度。最後，由於OIHP奈米粒子與共軛高分子之間具有能量轉移的優點，因此我們發現可製備穩定和可拉伸的發光奈米纖維並將其應用在LED元件中，這可以促進可穿戴電子元件的未來發展。

關鍵字

有機-無機材料 ； 鈣鈦礦複合材料 ； 形貌學 ； 電阻式記憶元件 ； 螢光

並列摘要

Organic-inorganic hybrid perovskite (OIHP) materials have been intensively studied in recent years due to their superior electronic and optical properties. Although, the material possesses such fascinating properties, there are significant limitations and challenges that affect device performance as well as mechanical and ambient stability. To overcome such disadvantages, one of the mostly adopted approach is the formation of the perovskite/polymer composite materials that can possess both perovskite and polymer properties. The work outlined herein particularly concerns OIHP nanoparticles (NPs) formation within the polymeric matrixes by taking advantages of chemical interactions between OIHP and polymers. In this thesis, the main idea is to study size control of OIHP nanocrystals and morphology of OIHP/polymer composites indicating the importance in different devices for data storage and light emitting applications. Two different solution based approaches will be presented to form film and nanofiber based OIHP NP/polymer composites. The details of each topic are summarized as below:
In chapter 2, OIHP (CH3NH3PbBr3) NPs was formed and well dispersed in an insulating solid polymer electrolyte (poly(ethylene oxide) (PEO)) benefiting the interaction between polymer and OIHP. It was revealed that PEO could serve as the chelating agent to coordinate with PbBr2/CH3NH3PbBr3 NPs in consequence of the direct interaction between Pb2+ cations and electron pairs of ether oxygen on the PEO chain to provide a host medium for the Pb2+ cations on both amorphous and crystalline phases. Herein, PEO was chosen not only to perform a matrix function due to formation of OIHP nanocrystals and PEO’s ionic conductivity but also to support a preservative material surrounding the OIHP NPs to improve their stability. Consequently, memory fabricated using this composite layer was showed resistive switching characteristic due to metallic filament formation in the derived device, leading to the write-once-read-many times resistive switching behavior.
In chapter 3, the OIHP (CH3NH3PbBr3) NP was growth in four different host polymers as polystyrene (PS), poly(4-vinylphenol) (PVPh), poly(methyl methacrylate) (PMMA), and poly(methacrylic acid) (PMAA). Existed dissimilar chemical interaction between the host polymers and perovskite was studied resulting in different OIHP NP size distribution and composite morphology. Each composite layer was utilized for a novel photomemory device showing distinct photo-response and memory behavior attributing to the different morphologies of the hybrid dielectric layers and the different sizes of the distributed OIHP NPs.
In chapter 4, co-axial (core-shell) electrospinning method was utilized to form OIHP NPs within thermoplastic polyurethane (TPU) nanofiber. Thanks to the existing chemical affinity between OIHP and TPU, NPs were well conserved and NP size distribution was limited by controlling solution parameters such as precursor composition, shell concentration as well as working conditions such as core-flow rate. Multi-color luminous OIHP nanofiber mats were achieved by changing the composition of OIHP precursor. Beside, hydrophobic TPU shell enhance mechanical stability of prepared fiber mats up to 100%-stretched state and it supports the ambient stability to the OIHP NPs up to one month. Lastly, intrinsic white light emitting nanofibers and white light emitting diode (LED) was demonstrated by taking advantage of energy transfer between OIHP NPs and conjugated polymers utilized in system.

並列關鍵字

Organic-Inorganic ； Perovskite Composite ； Morphology ； Electrical Memory ； Luminescence

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