Synthesis and Characterization of Quinoxaline-Based Thiophene Copolymers as Photoactive Layers in Organic Photovoltaic Cells

Bulletin of the Korean chemical society

Sang Jin Moon¹  Sang Kyu Lee¹  In Nam Kang¹  Woo hyung Lee¹  Won Suk Shin¹  Jong Wook Park¹  Jae Ryoung Kim¹  Yoon Suk Choi¹ 

关键词: Organic solar cell;    Quinoxaline;    Oligothiophene;    Thin film transistor;    Conjugated polymers;   

DOI  :  

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

A series of new quinoxaline-based thiophene copolymers (PQx2T, PQx4T, and PQx6T) was synthesized via Yamamoto and Stille coupling reactions. The Mws of PQx2T, PQx4T, and PQx6T were found to be 20,000, 12,000, and 29,000, with polydispersity indices of 2.0, 1.2, and 1.1, respectively. The UV-visible absorption spectra of the polymers showed two distinct absorption peaks in the ranges 350 - 460 nm and 560 - 600 nm, which arose from the π-π* transition of oligothiophene units and intramolecular charge transfer (ICT) between a quinoxaline acceptor and thiophene donor. The HOMO levels of the polymer ranged from ‒5.37 to ‒5.17 eV and the LUMO levels ranged from ‒3.67 to ‒3.45 eV. The electrochemical bandgaps of PQx2T, PQx4T, and PQx6T were 1.70, 1.71, and 1.72 eV, respectively, thus yielding low bandgap behavior. PQx2T, PQx4T, and PQx6T had open circuit voltages of 0.58, 0.42, and 0.47 V, and short circuit current densities of 2.9, 5.29 and 9.05 mA/cm2, respectively, when PC71BM was used as an acceptor. For the solar cells with PQx2T-PQx6T:PC71BM (1:3) blends, an increase in performance was observed in going from PQx2T to PQx6T. The power conversion efficiencies of PQx2T, PQx4T, and PQx6T devices were found to be 0.69%, 0.73%, and 1.80% under AM 1.5 G (100 mW/cm2) illumination.

【 授权许可】

Unknown