Synthesis of new acenaphtho[1,2-c]thiophene-based low bandgap polymers for organic photovoltaics

• Published in: Solar energy materials and solar cells Vol. 122; pp. 190 - 196
• Main Authors: Lee, Woo-Hyung, Kyu Lee, Sang, Suk Shin, Won, Moon, Sang-Jin, Park, Moo-Jin, Lee, Soo-Hyoung, Kang, In-Nam
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.2014; Elsevier
• Subjects: Acenaphtho[1,2-c]thiophene; Applied sciences; Conjugated polymer; Electrical engineering. Electrical power engineering; Electrical machines; Energy; Energy conversion efficiency; Exact sciences and technology; Heterojunction devices; Low bandgap; Molecular weight; Natural energy; Photovoltaic cells; Photovoltaic conversion; Polymers; Regulation and control; Semiconducting polymer; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy; Solubility; Thiophenes; Volatile organic compounds; Conjugated polymer; Semiconducting polymer; Acenaphtho[1,2-c]thiophene; Low bandgap; Multivariable control; Fullerene compounds; Conversion rate; Solubility; Thiophene; Organic solar cells; Energy level; Dione; Thermal stability; Butyric acid; Ester; Energy conversion; Acenaphtho[ 1,2-c]thiophene; Electron donor; Heterojunction
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2013.12.016

Donor–acceptor conjugated polymers, PDTTPDA and PDTTPDT, composed of new acenaphtho[1,2-c]thiophene or thiophene as electron donors and 1,3-dithien-2-yl-thieno[3,4-c]pyrrole-4,6-dione (DTTPD) as the electron acceptor were synthesized by a Stille cross-coupling reaction. These polymers combine interesting properties such as good solubility and excellent thermal stability. The weight-averaged molecular weights (Mw) of PDTTPDA and PDTTPDT were found to be 71,000 and 79,000 with polydispersity indices of 1.65 and 1.66, respectively. Photophysical studies revealed a low bandgap of 1.77eV for PDTTPDA and 1.72eV for PDTTPDT. The present study indicates that the combination of DTTPD and acenaphtho[1,2-c]thiophene building blocks can be a very effective way to lower the HOMO energy level and ultimately to enhance the Voc of polymer solar cells. The Voc reported here (up to 0.94V) is one of the highest observed in polymer:PCBM bulk heterojunction devices, and a power conversion efficiency (PCE) of up to 3.28% was observed in the PDTTPDA devices. •The synthesis and characterization of new acenaphtho[1,2-c]thiophene-based donor–acceptor (PDTTPDA) copolymer was described.•The influence of acenaphtho[1,2-c]thiophene groups in the polymer backbones were investigated with regard to device performances.•PDTTPDA displayed a high α, and low HOMO energy levels (−5.66eV), leading to a PCE of 3.28% and a VOC of 0.94V.