Synthesis, characterizations and photovoltaic applications of a thickness-insensitive benzodifuran based copolymer

A novel thienyl-free furan based copolymer of PBDFDFBO was synthesized and it exhibited a high hole mobility of 2.46 * 10 −3 cm 2 V −1 S −1 and a champion PCE of 11.23%. Impressively, device efficiency is insensitive to the variation of photoactive layer thickness and can maintain over 10.98% efficiency as film thickness increases to 600 nm, which is the best result for furan based organic solar cells. • A new thienyl-free furan based copolymer of PBDFDFBO was synthesized. • It exhibited an elegant hole mobility of 2.46 * 10 −3 cm 2 V −1 S −1 . • Its device efficiency is insensitive to the variation of photoactive layer thickness. Low toleration of thickness variations in the organic solar cells (OSCs), is currently becoming bottleneck challenges to achieve power conversion efficiencies (PCE) and large-scaled roll-to-roll device fabrication. In this work, a new thienyl-free furan-based copolymer of PBDFDFBO was synthesized via Stille copolymerization of benzodifuran (BDF) and 4,7-di(furan-2-yl)benzo[c][1,2,5]oxadiazole monomers. It exhibited a high hole mobility of 2.46 × 10 −3 cm 2 V −1 S −1 , which could be attributed to a planar molecular conformation of the polymer. When the polymer was selected as donor and small molecular ITIC-F as acceptor, the photovoltaic device results showed a champion PCE of 11.53% with a high V oc and FF. Impressively, device efficiency is insensitive to the variation of photoactive layer thickness and can maintain over 10.98% efficiency as film thickness increases to 600 nm, which is the best result for furan-based OSCs. The features of all furan-based polymer of PBDFDFBO provide great potential in developing thick film photovoltaic device and the efficient molecular design strategy also could be referenced to other photovoltaic materials.