Efficiency Improvement of Inverted Organic Solar Cells via Introducing a Series of Polyfluorene Dots in Electron Transport Layer

• Published in: Journal of physical chemistry. C 2015-07, Vol.119 (29), p.16462-16467
• Main Authors: Liu, Chunyu, Zhang, Xinyuan, Li, Zhiqi, He, Yeyuan, Li, Jinfeng, Shen, Liang, Zhang, Zhihui, Guo, Wenbin, Ruan, Shengping
• Format: Article
• Language: English
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.5b04079

This article describes a positive effect on improving the performance of organic solar cells (OSCs) by introducing a series of water-soluble polyfluorene (PF) dots. When poly­[(9,9-dioctyl­fluorenyl-2,7-diyl)-co-(1,4-benzo-1-thiadiazole)] (PF1), poly­(9,9-dioctyl­fluorenyl-2,7-diyl) (PF2), and poly­(9,9-dioctyl­fluorene)-co-(4,7-di-2-thienyl -2,1,3-benzothiadiazole) (PF3) dots are mixed into the polyethylenimine (PEI) cathode buffer layer, active layer and PEI films show an enhancement on light absorption in comparison with control film, which leads to the realization of poly­(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) solar cells with power conversion efficiency (PCE) of 4.33% for PF1 doping, 4.49% for PF2 doping, and 4.72% for PF3 doping, accounting for 23.0%, 27.6%, and 34.1% enhancement, respectively. Simultaneously, doping of PF dots also contributes to the improvement of exciton dissociation, charge transport, and charge collection. PF dots could be used as a dual functional additive to enhance optical and electrical properties for OSCs.