含苯並噻二唑及卡唑小分子衍生物之合成及其應用在有機太陽能電池之研究

Synthesis and Applications of Benzothiadiazole and Carbazole-Containing Molecules for Organic Solar Cell

蔣尚德(Shang-Te Chiang)

指導教授 ： 謝國煌

國立臺灣大學/工學院/化學工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.10271

摘要

在此研究中，為了開發新型有機太陽能電池材料，藉著鈴木(Suzuki coupling)及烏曼(Ullmann coupling)偶合，成功合成出以卡唑(carbazole)為主體，並且引入含有苯並噻二唑(benzothiadiazole)的施體-受體(donor-acceptor)結構的小分子，藉由改變共軛基團合成出具有卡唑、噻吩(thiophene)與甲氧基苯(methoxybenzene)的化合物O1、O2與O3。從熱重損失分析(thermogravimetry analysis, TGA)顯示化合物皆具有良好的熱穩定性(Td 5% > 300 oC)，由微差掃描熱卡計(differential scanning calorimetry, DSC)的結果可發現O1的星狀結構具有玻璃轉移溫度(Tg = 85.2 oC)，因為結構的扭曲，O1沒有熔點的產生；而O2及O3則具有結晶材料的熔點(Tm = 63.6, 128.7 oC)。由循環伏安法(cyclic voltammetry, CV)可以發現O1具有較高的氧化電位，由於其結構中卡唑的電子密度，造成在卡唑位置的氧化較難發生，而材料的最高填滿分子軌域(highest occupied molecular orbital, HOMO)能階落在-5.31~-5.44 eV之間。在紫外光/可見光吸收光譜(UV/Vis absoption spectra)中，隨著施體-受體結構的引入，各化合物的吸收光譜皆產生雙峰的圖形，較短波長的吸收(λAbs = 321 nm, 323 nm, 309 nm for O1, O2, O3)，隨著化合物不同的共軛基團而改變；較長波長的吸收(λAbs = 450 nm)，則因為相同施體-受體結構而落在相同波長，因此化合物的能隙皆為2.3 eV，而材料的最低未填分子軌域能階(lowest unoccupied molecular orbital, LUMO)落在-3.01~-3.14 eV之間。體異質接面太陽能電池元件的初步測試以化合物O1為主，與碳六十衍生物以重量比1:2混摻可以得到最佳的元件效率為0.013%，開路電壓0.65 V，短路電流0.067 mA/cm2，填充因子29.2%。

關鍵字

卡唑 ； 苯並噻二唑 ； 體異質接面 ； 有機太陽能電池

並列摘要

In this study, the carbazole derivatives with benzothiadiazole-containing donor-acceptor structure for organic solar cell have been successfully synthesized via Suzuki and Ullmann coupling. Carbazole-, thiophene- and methoxybenzene-containing conjugated group have been introduced into compound O1, O2 and O3. In thermogravimetry analysis, O1, O2, O3 were found with good thermal stability and 5% thermal degradation temperature over 300 oC. The glass transition temperature of O1 was observed and characterized by a differential scanning calorimetery at 85.2 oC, but no melting point was found due to its twisted structure. Melting point of O2 and O3 can be found at 63.6 and 128.7 oC. In cyclic voltammetry, the oxidation potential of O1 is higher than O2 and O3 due to its lower electron density. The HOMO of compounds was estimated at -5.31~-5.44 eV. The absorption spectra of above-mentioned compounds were found to be a two-peak diagram which can be attributed to their donor-acceptor structure. The shifting of short-wavelength absorption peak was observed in UV-Vis spectrum with changing different conjugated groups (λAbs = 321nm, 323nm, 309nm for O1, O2, O3 respectively). The long-wavelength absorption peak was found to be located at the same wavelength (λAbs = 450 nm) for 3 compounds for the same donor-acceptor structure. And the energy gap of compounds was found to be the same (2.3 eV) and their LUMO was estimated at -3.01~-3.14 eV. From all the properties analysis, O1, O2 and O3 are found to be the promising material for their applications in the bulk heterojunction organic solar cell. The preliminary bulk heterojunction solar cell devices were fabricated with compound O1. The best device with O1:PCBM = 1:2 shows power conversion efficiencies 0.013% with open-circuit voltage(VOC) of 0.65V, short-circuit current density (JSC) of 0.067 mA/cm2 and fill factor(FF) 29.2 % under AM1.5G solar simulator.

並列關鍵字

carbazole ； benzothiadiazole ； bulk heterojunction ； organic solar cell

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