新型含二苯順丁烯亞醯胺-噻吩之施體-受體雙能共聚高分子合成與光伏性質研究

本研究主要係以含有二苯順丁烯亞醯胺(3,4-diphenylmaleimide)及設計搭配不同噻吩衍生物，利用Stille Coupling反應，合成出一系列共聚高分子，應用於高分子太陽能電池。二苯順丁亞醯胺衍生物具有良好之熱穩定性以及溶解度，並可做為多種聚合物之共聚單體，進行多樣之化學反應。近期利用二苯順丁烯亞醯胺衍生物，做為高分子電激發光二極體之研究報導顯示，證實二苯順丁烯亞醯胺具有良好之傳遞電荷特性。為了能應用於高分子太陽能電池，首先我們利用二苯順丁烯亞醯胺與四噻吩進行共聚合反應。而為了更進一步提升太陽光光譜之吸收能力，將具有推電子能力之噻吩基團導入於二苯順丁烯亞醯胺衍生物。合成出之二苯順丁烯亞醯胺-噻吩衍生物再與不同稠環之噻吩衍生物進行共聚合反應，其目的為改善分子間之共平面性與增加共軛長度。所合成出之聚合物為無規則性高分子，具有分子內推-拉電子之結構，將使共聚物具有低能隙和寬廣吸收波段之特性。從DSC及TGA測量結果顯示，本研究所合成之聚合物其Tg值在45℃以上，且Td在405-437℃之間，顯示出具有良好之熱穩定性。由吸收光譜之實驗量測可發現，其吸收光譜範圍落在300-600 nm之間。利用此光譜可計算出之光學能階在2.17-2.38 eV。從固態薄膜之螢光光譜實驗可知，在PCBM摻混量為50 wt%以上時，有顯著淬息現象產生，此一現象顯示聚合物可將電子快速傳輸至PCBM中。由電化學性質顯示，此系列聚合物之HOMO能階介於5.27-5.67 eV，預期將來應用於光伏電池上，可呈現出良好之空氣穩定性及較高之開路電壓。

關鍵字

高分子太陽能電池；光伏電池；噻吩；二苯順丁烯亞醯胺

並列摘要

A series of copolymers containing 3,4-diphenyl-maleimide and different thiophene derivatives has been designed and synthesized via stille coupling for application in polymer solar cells (PSCs). The 3,4-diphenyl-maleimide derivative possess good thermal stability and solubility, and the great diversity chemical synthesis routes of this monomer have been developed to several polymers. Recently, 3,4-diphenyl-maleimide based PLEDs has been reported, which show good charge mobility. For use in PSCs, firstly we utilized 3,4-diphenyl-maleimide copolymerizing with quaterthiophene. In order to enhance light harvesting ability of solar spectrum, the electron-sufficient thiophenes were conducted into 3,4-diphenyl-maleimide unit. The 3,4-diphenyl-maleimide-thiophene derivatives, then copolymerized with different fused thiophene derivatives for improving the coplanarity and conjugation lengths. The resulting random copolymers exhibit electron donor-acceptor architectures, which promise the merits of low band gaps and broad absorption bands. From the DSC and TGA measurements, all the copolymers were thermally stable 405 up to 437℃ upon heating and showed Tg values over 45℃. Absorption spectra of these copolymers exhibited broad peaks located in the UV and visible regions form 300 to 650 nm with optical band gaps at 2.17-2.38 eV. The intensities of PL emission spectra in solid film of these copolymers were dramatically quenched by addition of 50 wt% PCBM. This is the consequence of ultrafast photoinduced charge transfer from the polymer to PCBM. Electrochemical properties indicated that the HOMO levels of these copolymers were in the range of 5.27-5.67 eV, which promise better air stability and high open circuit voltage (Voc) for photovoltaic cells application.