可作為染敏太陽能電池之8H-茚并-[2,1-b]-噻吩系光敏染料
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2015
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Abstract
本論文合成出一系列以結構較平面之8H-茚并-[2,1-b]-噻吩（indeno[1,2-b]thiophene，Idt）做為共軛架橋基之光敏染料，並應用於染料敏化太陽能電池。我們發現在染料結構中引入Idt片段有助於使吸收波長紅位移，甚至進入近紅外光區，增進光收成能力。在染料的結構設計上，我們以YR1染料為基礎，藉由染料結構之變化來調控HOMO/LUMO能階與光吸收性質，成功合成出YR系列染料。藉由循環伏安法(cyclic voltammetry)、差式脈衝伏安法（differential pulse voltammetry）以及可見-紫外光光譜儀(UV-Vis absorption spectra)，我們可以測得化合物在溶液狀態下的HOMO/LUMO能階，以及分子的光收成能力。同時，我們也對這些分子進行電化學阻抗、強度調製光電壓譜和理論計算之探討，以便深入探討分子結構與元件效率之關連性。
此外，我們發現將共軛片段由Idt的indene五元環處進一步延伸出去將有利於染料的光收成與增進光激發後電子注入TiO2之能力，使得其短路電流值與元件效率有所提升。經由一系列的量測後，我們發現相較於YR1−YR3染料，延伸了共軛片段之YR4−YR6染料其短路電流值有顯著地提升。YR6染料在加入CDCA (chenodeoxycholic acid)為共吸附劑後效率更可達5.06% (光電流，13.71 mA cm-2；光電壓，0.604 V；填充因子，0.61 )，為N719建構標準元件之67%。
A series of organic sensitizers featuring a planar indeno[1,2-b]thiophene (Idt) as the π-linker of a bridging unit for dye-sensitized solar cells (DSSCs) were synthesized. The introduction of Idt segment was found to be beneficial for red-shifting the absorption wavelength up to the near-infrared region and therefore enhancing the light-harvesting ability. With the triphenylamine(TPA)−Idt−cyanoacrylic acid compound (YR1) as a reference compound, various synthetic strategies had been used for tuning the light-harvesting properties and the HOMO/LUMO energy levels of the molecule. The physical properties of the sensitizers were systematically investigated by cyclic voltammetry, differential pulse voltammetry and UV-Vis absorption spectra. Electrochemical impedance (EIS) and intensity modulated photovoltage spectroscopic (IMVS) studies, and theoretical computations were also carried out on these dye molecules for correlation between the molecular structure and the cell performance. Extending the π-linker on the phenyl group of Idt is beneficial to both light-harvesting and electron injection, which results in an improvement in both short-circuit photocurrent density (Jsc) and the overall power conversion efficiency (PCE). Under standard AM 1.5G solar illumination, DSSCs based on YR4−YR6 showed a remarkable increase in short-circuit photocurrent compared to those based on YR1−YR3. Upon addition of chenodeoxycholic acid (CDCA) as the co-adsorbent, the DSSC of YR6 showed an overall power conversion efficiency (PCE) of 5.06% (short-circuit photocurrent density (Jsc), 13.71 mA cm-2; open-circuit photovoltage (Voc), 0.604 V; fill factor (FF), 0.61), which reached 67% of N719-based DSSCs fabricated and measured under similar condition.
A series of organic sensitizers featuring a planar indeno[1,2-b]thiophene (Idt) as the π-linker of a bridging unit for dye-sensitized solar cells (DSSCs) were synthesized. The introduction of Idt segment was found to be beneficial for red-shifting the absorption wavelength up to the near-infrared region and therefore enhancing the light-harvesting ability. With the triphenylamine(TPA)−Idt−cyanoacrylic acid compound (YR1) as a reference compound, various synthetic strategies had been used for tuning the light-harvesting properties and the HOMO/LUMO energy levels of the molecule. The physical properties of the sensitizers were systematically investigated by cyclic voltammetry, differential pulse voltammetry and UV-Vis absorption spectra. Electrochemical impedance (EIS) and intensity modulated photovoltage spectroscopic (IMVS) studies, and theoretical computations were also carried out on these dye molecules for correlation between the molecular structure and the cell performance. Extending the π-linker on the phenyl group of Idt is beneficial to both light-harvesting and electron injection, which results in an improvement in both short-circuit photocurrent density (Jsc) and the overall power conversion efficiency (PCE). Under standard AM 1.5G solar illumination, DSSCs based on YR4−YR6 showed a remarkable increase in short-circuit photocurrent compared to those based on YR1−YR3. Upon addition of chenodeoxycholic acid (CDCA) as the co-adsorbent, the DSSC of YR6 showed an overall power conversion efficiency (PCE) of 5.06% (short-circuit photocurrent density (Jsc), 13.71 mA cm-2; open-circuit photovoltage (Voc), 0.604 V; fill factor (FF), 0.61), which reached 67% of N719-based DSSCs fabricated and measured under similar condition.
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染料敏化太陽能電池, 8H-茚并-[2, 1-b]-噻吩, 共吸附, DSSCs, indeno[1, 2-b]thiophene, co-adsorbent