Synthesis of a novel low-bandgap polymer based on a ladder-type heptacyclic arene consisting of outer thieno[3,2-b]thiophene units for efficient photovoltaic application

• Main Authors: Xu, Xiaofeng, Cai, Ping, Lu, Yong, Choon, Ng Siu, Chen, Junwu, Ong, Beng S., Hu, Xiao
• Other Authors: School of Chemical and Biomedical Engineering
• Format: Article
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Chemical engineering
• Online Access: https://hdl.handle.net/10356/102771; http://hdl.handle.net/10220/19114
• Institution: Nanyang Technological University

A novel conjugated polymer PIDTT-quinoxaline (Qx) based on the coplanar thieno[3,2-b]thiophene-phenylene-thieno[3,2-b]thiophene structure is synthesized and evaluated as an electron-donor material for bulk-heterojunction polymer solar cells (BHJ PSCs). The absorption spectra, electrochemical, charge transport, and film morphology properties as well as theoretical modeling of PIDTT-Qx are investigated to understand its intrinsic structure–property relationship. As expected, this polymer with an extended π-conjugated backbone exhibits a narrow-bandgap and board absorption spectrum for enhanced light harvesting. BHJ PSCs (ITO/PEDOT:PSS/polymer:PC71BM/interlayer/Al) afford a maximum power conversion efficiency of 5.05% with an open-circuit voltage of 0.84 V, a short-circuit current density of 11.26 mA cm−2, and a fill factor of 53.4%. These results demonstrate the potential of PIDTT-Qx as an efficient electron-donor material for BHJ PSCs.