| 摘要: | 本研究以金屬鍶鹽和羧酸有機配子反應，合成一系列金屬有機骨架化合物，並研究其介電性質和光物理特性。化合物{[Sr2(1,3-bdc)2(H2O)2]•H2O}n (1) 與 {[Sr(ntc)(H2O)2]•H2O}n (4)為二維結構，均為單斜晶系，其空間群分別為C2/c 與 P21/c。而化合物 [Sr(Hbtc)(H2O)]n (2) 為二維結構，以三個配位羧酸基Hbtc2– 與鍶離子建構成三維化合物 {[Sr(H2btc)2(MeOH)(H2O)2]•2H2O}n (3)。化合物1在移除極性客分子之後，顯現低介電性質 (κ = 2.4)。此外化合物1移除客分子之後仍保留其結晶性，熱穩定性高達420 °C。低介電性與良好熱穩定性使化合物1具有高潛力之積體電路層間介電層材料 (ILD)。本研究對金屬有機骨架(low-κ MOFs)材料低介電性質量測，配合文獻報告之理論計算及元件製備等之研究顯示低介電性質金屬有機骨架材料 (low-κ MOFs)卻有潛力成為積體電路層間介電層材料(ILD)。化合物2經過理論計算與實驗量測確認有顯著半導體特性。在室溫交流電導常數、相對介電常數和光致發光光譜證明化合物2擁有1.94 eV能階帶隙，與其他常用半導體材料如MoS2, CdSe, CdTe, ZnTe and GaP等性質相近。這是第一份鍶金屬有機骨架應用於半導體材料之結果，有很大的意義。化合物3於藍色光區有寬的發光帶，其Commission International ed’Eclairage (CIE) 座標為 (0.196, 0.191) 。這種藍色光致發光是由於配位基的發光、π–π堆疊交互作用與電荷轉移機制所貢獻。在開發固態白光發光元件方面，藍光超分子是非常有潛力的。應用光致發光光譜概念，本論文研究接著設計白色發光材料，實驗發現二維鍶金屬有機骨架 {[Sr(ntc)(H2O)2]•H2O}n (4) 化合物為優益白光發光材
料，其Commission International ed’Eclairage (CIE) 座標為 (0.336; 0.383) 其對應之色溫 (color temperature) 為5389 K。這種白色光致發光是由於配位基之π–π堆疊交互作用與電荷轉移機制所貢獻。鍶金屬有機骨架化合物3和4之設計開發對高效節能固態照明材料之研究提供新的方向。
;In this thesis, a series of metal–organic frameworks (MOFs) and a supramolecular compound were synthesized by reacting carboxylate group-containing ligands with a strontium metal salt and their dielectric and optical behavior were investigated. Compounds {[Sr2(1,3-bdc)2(H2O)2]•H2O}n (1) and {[Sr(ntc)(H2O)2]•H2O}n (4) adopt 2D layered structures with a monoclinic C2/c and P21/c space groups, respectively. While the 2D layers of compound [Sr(Hbtc)(H2O)]n (2) are extended into a 3D network through a third carboxylate group of an Hbtc2– ligand. Compound {[Sr(H2btc)2(MeOH)(H2O)2]•2H2O}n (3) is a supramolecular compound that forms an extended structure via exemplary hydrogen-bonding with the guest molecules. Compound 1 exhibited significantly low dielectric behavior (κ = 2.4) upon the removal of its polar guest molecules. In addition, the dehydrated compound 1 retained its crystalline morphology and showed a high thermal stability at temperatures of up to 420 °C. Such a low dielectric constant with good thermal stability and low leakage current suggests that it might be useful as an interlayer dielectric (ILD) in integrated circuits. We also highlighted an initial study on low-κ MOFs and categorized the research on MOFs as an ILD into three major areas, 1) theoretical calculations, 2) fundamental properties, and 3) device integration. The highlighted results will trigger research and innovation on MOFs as ILDs in terms of providing electronic devices incorporating MOFs. Compound 2 exhibits remarkable semiconducting behaviour as evidenced by theoretical calculations and experimental measurements. Near room temperature ac conductivity, relative permittivity, and photoluminescence spectrum provide strong proof that compound 2 owns a band gap of 1.94 eV, which is comparable with other commonly used semiconducting materials e.g. MoS2, CdSe, CdTe, ZnTe and GaP etc. This first report on Sr-based MOF as a semiconductor promises to pave the way for further studies in semiconducting MOFs with interesting potential applications in
optoelectronic devices. Compound 3 exhibits remarkable broad band photoluminescence spectra with a blue light emission with Commission International ed’Eclairage (CIE) coordinates at (0.196, 0.191). Such broad photoluminescence spectrum for blue light is due to the ligand-based emission, raised by its π–π stacking interactions and charge transfer mechanisms that are contributed by the crystal structure of 3. The design of a blue emitting supramolecular network is very influential for developing white light emitting devices for solid-state lighting applications. Utilizing the concept of producing photoluminescence spectra over a wide range, we are able to design an intrinsic white light emitting material (compound 4). The two dimensional strontium-based metal–organic framework {[Sr(ntc)(H2O)2]•H2O}n (4) shows a remarkable intrinsic white light emission photoluminescence with Commission International ed’Eclairage (CIE) coordinates at 0.336; 0.383) with a color temperature around 5389 K. Such a broad photoluminescence spectrum for white light is due to the ligand-based emission arising from the contribution of its strong π–π stacking interactions and charge transfer mechanism. The design of these Sr-based compounds 3 and 4 promise to open up new perspectives for developing high-performance energy-saving solid-state lighting materials. |
