title: Polyfluorene Electrolytes Interfacial Layer for Efficient Polymer Solar Cells: Controllably Interfacial Dipoles by Regulation of Polar Groups.
abstract: The polar groups in the conjugated polyelectrolytes (CPEs) can create the favorable dipoles at the electrode/active layer interface, which is critical for the CPEs to minimize the interfacial energy barrier in polymer solar cells (PSCs). Herein, a series of CPEs based on poly [(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-co-2,7-(9,9-dioctylfluorene)] derivates (PFNs) (PFN30, PFN50, PFN70, and PFN100) with different mole ratio of polar groups (-N(C2H5)2) were designed and synthesized to investigate the effect of the numbers of polar groups on the interfacial dipoles. Controllably interfacial dipoles could be readily achieved by only tuning the numbers of -N(C2H5)2 in PFNs, as revealed by the work function of the PFNs modified ITO gradually reduced as the loadings of the -N(C2H5)2 increased. In addition, increasing the numbers of -N(C2H5)2 in PFNs were also favorable for developing the smooth and homogeneous morphology of the active layer. As a result, the content of the polar amine in the PFNs exerted great influence on the performance of polymer solar cells. Increasing the numbers of the pendent -N(C2H5)2 could effectively improve the power conversion efficiency (PCE) of the devices. Among these PFNs, PFN100 with the highest content of -N(C2H5)2 polar groups delivered the device with the best PCE of 3.27%. It indicates tailoring the content of the polar groups in the CPEs interlayer is a facial and promising approach for interfacial engineering to developing high performance PSCs.
authors.affiliation: College of Chemistry/Institute of Polymers, Nanchang University , 999 Xuefu Avenue, Nanchang 330031, China.
authors.forename: Huimin
authors.initials: H
authors.lastname: Liu
authors.affiliation: College of Chemistry/Institute of Polymers, Nanchang University , 999 Xuefu Avenue, Nanchang 330031, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Hu
authors.affiliation: College of Chemistry/Institute of Polymers, Nanchang University , 999 Xuefu Avenue, Nanchang 330031, China.
authors.forename: Feiyan
authors.initials: F
authors.lastname: Wu
authors.affiliation: College of Chemistry/Institute of Polymers, Nanchang University , 999 Xuefu Avenue, Nanchang 330031, China.|Jiangxi Provincial Key Laboratory of New Energy Chemistry, Nanchang University , 999 Xuefu Avenue, Nanchang 330031, China.
authors.forename: Lie
authors.initials: L
authors.lastname: Chen
authors.affiliation: College of Chemistry/Institute of Polymers, Nanchang University , 999 Xuefu Avenue, Nanchang 330031, China.|Jiangxi Provincial Key Laboratory of New Energy Chemistry, Nanchang University , 999 Xuefu Avenue, Nanchang 330031, China.
authors.forename: Yiwang
authors.initials: Y
authors.lastname: Chen
keywords: conjugated polyelectrolytes; interfacial dipoles; interfacial engineering; polar groups; polymer solar cells