Naphthodifuran-based zigzag-type polycyclic arene with conjugated side chains for efficient photovoltaicsElectronic supplementary information (ESI) available. See DOI: 10.1039/c7cp02283b

• Main Authors: Peng, Hongjian, Luan, Xiangfeng, Feng, Liuliu, Yuan, Jun, Zhang, Zhi-Guo, Li, Yongfang, Zou, Yingping
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c7cp02283b

Ladder-type conjugated structures with rigid and coplanar molecular frameworks feature longer effective conjugation, affirmative optoelectronic properties and strong intermolecular π-π interactions, which are ideal characteristics for organic photovoltaics. Here, a new "zigzag" angular-fused naphthodifuran (zNDF) based on alkoxyphenyl side chains was designed and synthesized. The distannylated zNDF building block was copolymerized with 4,7-di(5-bromothiophen-2-yl)-5,6-dioctyloxybenzo[ c ][1,2,5]thiadiazole and 5,8-bis(5-bromothiophen-2-yl)-2,3-bis(4-(2-ethylhexyloxy)-3-fluorophenyl)-6,7-difloroquinoxaline (Br-BT and Br- ff Qx) acceptor units by Stille cross coupling reaction to form two new medium bandgap donor-acceptor polymers PzNDFP-BT and PzNDFP- ff Qx , respectively. The photovoltaic properties of the copolymers blended with [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM) as an electron acceptor were investigated. A 6.9% efficiency was achieved from the single device based on the PzNDFP-BT  : PC 71 BM (1 : 1.5, w/w) blend film with a 0.25% 1,8-diiodooctane (DIO) additive, which is among the highest efficiency for zNDF-based polymer solar cells. Two alkoxyphenyl-substituted naphthodifuran (zNDF)-based polymers ( PzNDFP-BT and PzNDFP- ff Qx ) were synthesized. A promising PCE of 6.9% has been obtained, which is the highest PCE among zNDF-based polymers to date.