Synthesis and Applications of 5,6-Difluoro-benzo-2,1,3-thiadiazole Based Conjugated Polymers with Light Harvesting Groups and Diketopyrrolopyrrole Based Conjugated Polymers

• Main Authors: Peng, Shih-Hao, 彭士豪
• Other Authors: Hsu, Chain-Shu
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/b3bmq2

博士 === 國立交通大學 === 應用化學系碩博士班 === 105 === This research is aimed to enhance the performances of low band gap (LBG) polymer in the optoelectronic applications, such as organic field-effect transistors (OFETs) and organic polymer photovoltaics (OPVs). First part, we introduce the different light harvesting groups in the polymer chains. Broadening the absorptions has the potential to increase the short-circuit current. In this study, we synthesized different random copolymers by introducing the light harvesting groups in the side chains to enhance the light absorption. Moreover, we investigated the characteristics and the power conversion efficiency.The porphyrin side chain units were introduced to the PTh4FBT polymers to increase the absorption in blue-light region. PTh4FBT-Por-Py not only enhance the absorption of blue-light region, but also had the high PCE value of 8.0%. In comparison with PTh4FBT-Por-Py, PTh4FBT-DiPor-Py had much more enormous side chains. The gigantic side chains destroyed the stacking of the polymers. Though PTh4FBT-DiPor-Py increased the absorption of blue-light region and red-light region, but got low PCE value of 2.3%. Ternary organic solar cells are emerging as a promising strategy to enhance device power conversion efficiency by broadening the range of light absorption through the incorporation of additional light-absorbing components. When we blended PTh4FBT-Por-Py with PTB7, the PCE value could enhance from 7.1% to 8.2%. Moreover, the PCE value of blending with PTB7-Th grew from 8.1% to 9.0%. Next, we used the perylene as smaller side shains in PTh4FBT to synthesized PTh4FBT-Pery-1 and PTh4FBT-Pery-2. The side chains of perylene could contribute to promote the absorption blue-light region. In comparison with PTh4FBT-Pery-1, PTh4FBT-Pery-2 had more proportion of perylene. When we enhanced the ratio of perylene, the much more blue-light could be absorbed. Thus, the PCE value of PTh4FBT-Pery-2 was higher than PTh4FBT-Pery-1. In the third part, the new donor-acceptor (D-A) conjugate polymers based on 3,6-bis(2-bromothieno-[3,2-b]thiophen-5-yl)-2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]-pyrrole-1,4-(2H,5H)-dione (Br-TTDPP) combined with three different electron-donating monomers bithiophene (BT), di(2-thienyl)ethene (TVT), di(selenophene-2-yl)ethene (SVS) were synthesized. The optical band gap, electrochemical properties and organic field-effect transistors (OFETs) device performance of TTDPP-based polymers were systematically investigated. X-ray diffraction (XRD) was used to evaluate the molecular packing of TTDPP-based polymers. Among three polymers, TTDPP-SVS showed the smallest d-spacing and largest distance of 0.372 for π-π stacking. In paticular, a OTFT having a TTDPP-SVS active layer showed the highest hole mobility of 0.196 cm2 V-1 s-1, the lowest threshold voltage down to -3.6 V, and the highest Ion/Ioff ratio of 6.5×104. This indicate that π-extened SVS significantly improves charge transport properties.