含卡唑及苯並噻二唑小分子之合成、特性及其於有機太陽能電池應用上之研究

Abstract

本研究的目的為利用鈴木偶合法(Suzuki coupling)合成出一系列新穎的含有卡唑(carbarzole)、苯並噻二唑(Benzothiadiazole)以及噻吩(thiophene)的施體-予體(donor-acceptor)結構的低能隙小分子(CZTHnBTester)。為了延長共軛長度，夾在carbazole和Benzothiadiazole中間的thiophene的個數從一個增加到三個(n=1~3)。從熱重損失分析可以發現三組小分子都有良好的熱穩定性，可以承受元件製程的溫度。這三組小分子在吸收光譜上皆有兩個吸收峰，且成膜後會有明顯的紅移；thiophene的個數增多，吸收光譜也會有相當的紅移發生，有著更廣的吸收。計算出的能隙值則是為1.80到1.98 eV。把PCBM當成予體，CZTH1BTester當做施體去製成的混摻異質接面(bulk heterojunction)太陽能電池元件，最好的效率值為0.24 % ，其中開路電壓(Voc)為0.49 V，短路電流(Jsc)為1.63 mA/cm2，填充因子(FF)為30 %。

In this study, a series of novel electron donor-acceptor low-bandgap moleculars (CZTHnBTester) which composed of carbazole, benzothiadiazole, thiophene units were synthesized by Suzuki coupling. To extend its conjugated length, the number of thiophene between carbazole and benzothiadiazole was increased from 1 to 3. In thermogravimetry analysis, the three moleculars were found with good thermal stability. All these moleculars displayed two absorption bands in absorption spectra and exhibit a noticeable red shift when they were in film. Increasing the number of thiophene also caused a evident shift and had broader absorptive ranges. The optical band gap showed to 1.8 to 1.98 eV by absorption onset. Bulk heterojunction solar cells (PSCs) fabricated with these oligomers as the donor materials and PCBM as the acceptor material exhibited best power conversion efficiencies up to 0.24 % with the open circuit voltages of 0.49 V, short circuit currents of 1.63 mA/cm2 and fill factor of 30 %.