設計和合成新型共軛有機/高分子材料對於太陽能電池和金屬離子感測器之應用

Abstract

本論文的核心目標是研究聚合物/小分子總體異質接面太陽能電池具低能帶隙 (LBG) 共軛予體 - 受體聚合物/小分子作為電子予體的性能。在本論文的第一章，我們介紹了聚合物/小分子太陽能電池，並總結了近年來的文獻。這些D-A共軛聚合物/小分子具有寬的吸收敏化作用在300-700nm的區域。 LBG聚合物/小分子的最高佔據分子軌道 (HOMO) 和最低未佔據分子軌道 (LUMO) 能階均在理想的能階範圍內。由於這些性質，(6,6)- phenyl-C61-butyric acid methyl ester (PC61BM)做為電子予體或(6,6)-phenyl-C71-butyric acid methyl ester (PC71BM) 做為電子受體被應用在總體異質結 (BHJ) 聚合物/小分子太陽能電池。除了太陽能電池的研究之外，我們還研究了水溶性共軛分子用於金屬感測器。在論文的第二章中，我們描述了幾種化學感測機制，近年來已經開發了幾種用於水溶液中對 Hg2+ 具有選擇性感測的探頭。 在第三章中，一系列的予體 - 受體 (D-A) 聚合物 (P1-P3) 基於benzodithiophene (BDT) 和電子受體 benzotriazole (BTZ)單元，使用thiophene作為連接體，探討了具有/不具有烷基側鏈，這些聚合物 (P1-P3) 藉由 Stille 偶聯聚合法合成。具有多個氟化BTZ基團的聚合物對於熱學，光學，電化學和光伏性質的影響也都一一被研究與探討。這些聚合物具有最高的佔據分子軌道 (HOMO) 能階範圍為-5.38至-5.6eV，最低未佔分子軌道 (LUMO) 能階範圍為-3.55至-3.57eV，其涵蓋了低光學帶隙的寬吸收範圍。總體異質結 (BHJ) 聚合物太陽能電池元件其D-A聚合物主動層，混合了不同重量比的電子受體 [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM)，聚合物P3的PSC元件在100 mW cm-2的AM 1.5白光照明下獲得的最大功率轉換效率 (PCE) 值3％（Jsc = 7.70 mA/cm2，FF = 54.04和Voc = 0.72V）。 在第四章中，我們報導了一組由benzo dithiophene (BDT) 單元作為予體 (D) 的π共軛A-D-A型小分子 (SMs) 包含氟取代苯環作為受體 (A) 的benzotriazole (BTZ) 單元以及具有側鏈thiophene端基的合成，材料性質和總體異質結 (BHJ) 太陽能電池特性。在這些系統 (2F BTZ-BDT and 3FBTZ-BDT) 中，BTZ苯環上的側鏈和多個氟的取代極大地影響了BHJ太陽能電池中的分子堆疊，光學，電化學，薄膜形態和光伏特性。這些SMs具有最高佔據分子軌道 (HOMO) 能階範圍-5.32至-5.68eV，最低未佔分子軌道 (LUMO) 能階範圍為-3.16至-3.70eV，其涵蓋了低光學帶隙的寬吸收範圍。 3FBTZ-BDT與PC71BM的功率轉換效率 (PCE) 值達到1.76％（Jsc = 6.07 mA/cm2，FF = 33.87，Voc = 0.86V）。 在第五章中，我們設計和合成了一種新的紅色螢光汞離子感測材料，含有分叉的軟鹼原子N和S的鑷狀親水探針與2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) 單元。由於TCF單元具有高度電子接受的性質 (作為拉推電子色團)z該感測材料在100％水性介質中對各種的金屬離子進行測試，發現對於Hg 2+具有選擇性，其檢測結果可以透過肉眼和光致發光 (PL) 觀測 。經由理論和時間解析光致發光的測量，更進一步證實探針對於 Hg2+ 選擇性和可逆性是透過感測材料的分子間電荷轉移機制。此外，感測材料在活細胞中對於 Hg2+ 的偵測也透過共焦螢光圖像來進行測試。最後，優異的吸收變化和螢光淬息光譜現象，使我們第一次驗證了TCF片段對於 Hg2+ 具有選擇性的光學指示劑。

The core objective of this dissertation is to study the performance of polymer/small-molecule bulk heterojunction solar cell involving low band-gap (LBG) conjugated donor-acceptor polymers/small-molecules as electron donors. In the first chapter of this thesis, we gave an introduction of polymer/small-molecule solar cells, and summarized the literature in the recent years. These D-A conjugated polymers/small-molecules possessed broad absorption sensitization in the region of 300-700 nm. Both highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the LBG polymers/small-molecules were within the desirable range of ideal energy levels. Because of these properties, these were applied to bulk heterojunction (BHJ) polymer/small-molecule solar cell as electron donors with (6,6)- phenyl-C61-butyric acid methyl ester (PC61BM) or (6,6)-phenyl-C71-butyric acid methyl ester (PC71BM) as an acceptor. Apart from the solar cell studies, we also studied water soluble conjugated molecules for metal sensor applications. In the second chapter of the thesis we have described about several chemosensing mechanisms several sensing probes have been developed for selective sensing of Hg2+ in aqueous solutions in recent years. In the third chapter, a series of donor–acceptor (D–A) polymers (P1-P3) based on benzodithiophene (BDT) and electron-accepting benzotriazole (BTZ) units containing thiophene linkers with/without alkyl side-chains were designed and synthesized via Stille coupling polymerization method. The effects of polymers with multiple fluorinated BTZ groups on their thermal, optical, electrochemical, and photovoltaic properties were investigated. These polymers possessed the highest occupied molecular orbital (HOMO) levels ranged -5.38 to -5.6 eV and the lowest unoccupied molecular orbital (LUMO) levels ranged -3.55 to -3.57 eV, which covered broad absorption ranges with low optical bandgaps. The bulk heterojunction (BHJ) polymer solar cell (PSC) devices containing an active layer of D-A polymers blended with different weight ratios of electron-acceptor [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) were explored under 100 mW cm-2 of AM 1.5 white-light illumination, where the maximum power conversion efficiency (PCE) value of 3% (with Jsc = 7.70 mA/cm2, FF = 54.04, and Voc = 0.72 V) was obtained in the PSC device consisting of polymer P3. In the fourth chapter, we report on the synthesis, material properties, and bulk heterojunction (BHJ) solar cell characteristics of a set of π-conjugated A-D-A type small-molecules (SMs) composed of benzo dithiophene (BDT) unit as donor (D) and benzotriazole (BTZ) unit consisting fluorine-substituted benzene ring as acceptor (A) along with thiophene end groups consisting alkyl-chains. In these systems (2F BTZ-BDT and 3FBTZ-BDT), the presence of alkyl chains and multiple fluorine substituted on phenyl ring of BTZ critically impact on molecular packing, optical, electrochemical, thin-film morphologies and photovoltaic properties in BHJ solar cells. These SMs possessed the highest occupied molecular orbital (HOMO) levels ranged -5.32 to -5.68 eV and the lowest unoccupied molecular orbital (LUMO) levels ranged -3.16 to -3.70 eV, which covered broad absorption ranges with low optical bandgaps. 3FBTZ-BDT attained the power conversion efficiency (PCE) value of 1.76% ( Jsc = 6.07 mA/cm2, FF = 33.87, and Voc = 0.86 V) with PC71BM. In the fifth chapter, A new red-fluorescent mercury ion sensor material is designed and synthesized, which is composed of a tweezer-shaped hydrophilic probe containing bifurcated soft-base atoms N and S coupled with 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) unit. By virtue of the strong electron-accepting nature of TCF unit (as a push-pull chromophore), this designed sensor material can selectively detect Hg2+ over various tested metal ions in a 100% aqueous medium via naked-eye and photoluminescence (PL) observations. Theoretical and time-resolved photoluminescence measurements further confirmed the selectivity and reversibility of the probe towards Hg2+ via intramolocular charge transfer mechanism in this sensor material. Moreover, the living cell tests by confocal fluorescence images of this sensor material towards Hg2+ were also investigated. Finally, distinguished absorption changes and fluorescence quenching spectral appearances allowed us to present the selective optical indicator of Hg2+ via TCF moiety for the first time.