Synthesis and Characterization of P-type Copolymers Containing Tetraphenylpyrrole and Thiophene Moieties

[[abstract]]本研究係以3,4-bis(4-bromophenyl)-1-ethyl-2,5-diphenyl-1H-pyrrole（四苯基吡咯衍生物）為主要單體，搭配不同噻吩衍生物為共聚單體，合成出一系列含四苯基吡咯-噻吩之具傳電洞特性p-型共聚高分子─PTPP-Th、PTPP-biTh與PTPP-biOTh，應用於單層異質接面型高分子太陽能電池。近期文獻報導，利用四苯基吡咯衍生物製作出小分子有機發光二極體，證實四苯基吡咯具有良好之電荷傳輸特性；藉由導入四苯基吡咯衍生物至高分子骨架中，可降低其HOMO能隙，預期將具有更好之空氣穩定性。此外，利用四苯基吡咯製作太陽能電池之吸光材料，目前尚未有任何文獻被發表。為了調控與增加太陽能光譜的吸收範圍，本實驗導入不同個數與長烷鏈取代基與否之噻吩衍生物，目的在於增進電洞傳輸率、共平面性、共軛長度和溶解度；設計無規則性之共聚高分子，其目的在於藉由不同團鏈的吸收光譜，期望達到增加吸收光譜範疇之目的。 研究結果顯示，此系列高分子之Td點皆大於300 ℃，顯示這些高分子具有良好之熱性質。吸收光譜的量測顯示出藉由利用無規則性共聚高分子之系統，我們可以提升其太陽光之吸收能力。在螢光光譜實驗中可發現，將不同比例之PCBM與高分子進行摻混，其螢光淬息現象非常明顯，代表這些材料在與PCBM摻混後，可以順利把電子由高分子傳至PCBM。由電化學實驗觀察得知，此系列之高分子其HOMO值約為5.42 ~ 5.49 eV，相較於P3HT為5.29 eV，有更高之HOMO值，證明其有較好的空氣穩定性與更高之開路電壓，以利於將來應用於高分子太陽能電池。[[abstract]]In this study, we utilized tetraphenylpyrrole derivatives (3,4-bis(4-bromophenyl)-1-ethyl-2,5-diphenyl-1H-pyrrole) as the main monomer and different thiophene derivatives as comonomers to synthesize three p-type tetrapenylpyrrole-thiophene based copolymer – PTPP-Th, PTPP-biTh, and PTPP-biOTh for application in bulk-heterojunction polymer solar cells. Recently, a series of tetraphenylpyrrole-based OLEDs has been reported, and it showed that tetraphenylpyrrole derivatives displayed good charge mobility. By introducing tetraphenylpyrrole unit into polymer backbone, the HOMO energy level is lowered, which promises better air stability. Moreover, tetraphenylpyrrole derivatives as BHJ polymer solar cells for light harvesting active layer has not been reported. To adjust and enhance the absorption range of the solar spectrum, our research incorporates thiophene derivatives with different numbers and with/without alkyl chain substituted judiciously for improving hole mobility, coplanarity, conjugated length, and solubility. The concept of using random copolymers is further to enhance the absorbance of solar spectrum. The Tds of these copolymers are all above 300 ℃, which indicate that these copolymers exhibited better thermal properties. Absorption measurements revealed that the harvesting ability has been improved by utilizing random copolymer systems. The photoluminescence emission intensity in thin film are quenched obviously after blended with different ratio of PCBM, which suggest ultrafast photoinduced charge transfer from polymer to PCBM. Electrochemical study present that the HOMO levels of these copolymers are around 5.42 ~ 5.49 eV in comparison with that of 5.29 eV for P3HT, which promised better air stability and a high open circuit voltage (Voc) for OPVs.[[note]]碩