title: Efficient Polymer Solar Cells by Lithium Sulfonated Polystyrene as a Charge Transport Interfacial Layer.
abstract: In this paper, we report the highly efficient bulk heterojunction (BHJ) polymer solar cells (PSCs) with an inverted device structure via utilizing an ultrathin layer of lithium sulfonated polystyrene (LiSPS) ionomer to reengineer the surface of the solution-processed zinc oxide (ZnO) electron extraction layer (EEL). The unique lithium-ionic conductive LiSPS contributes to enhanced electrical conductivity of the ZnO/LiSPS EEL, which not only facilitates charge extraction from the BHJ active layer but also minimizes the energy loss within the charge transport processes. In addition, the organic-inorganic LiSPS ionomer well circumvents the coherence issue of the organic BHJ photoactive layer on the ZnO EEL. Consequently, the enhanced charge transport and the lowered internal resistance between the BHJ photoactive layer and the ZnO/LiSPS EEL give rise to a dramatically reduced dark saturation current density and significantly minimized charge carrier recombination. As a result, the inverted BHJ PSCs with the ZnO/LiSPS EEL exhibit an approximatively 25% increase in power conversion efficiency. These results indicate our strategy provides an easy, but effective, approach to reach high performance inverted PSCs.
authors.affiliation: Department of Polymer Engineering, College of Polymer Science and Polymer Engineering, The University of Akron , Akron, Ohio 44325, United States.
authors.forename: Kai
authors.initials: K
authors.lastname: Wang
authors.affiliation: Department of Polymer Engineering, College of Polymer Science and Polymer Engineering, The University of Akron , Akron, Ohio 44325, United States.
authors.forename: Zhan
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Polymer Engineering, College of Polymer Science and Polymer Engineering, The University of Akron , Akron, Ohio 44325, United States.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Polymer Engineering, College of Polymer Science and Polymer Engineering, The University of Akron , Akron, Ohio 44325, United States.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Fu
authors.affiliation: Department of Polymer Engineering, College of Polymer Science and Polymer Engineering, The University of Akron , Akron, Ohio 44325, United States.|State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, P. R. China.
authors.forename: Wenzhan
authors.initials: W
authors.lastname: Xu
authors.affiliation: Department of Polymer Engineering, College of Polymer Science and Polymer Engineering, The University of Akron , Akron, Ohio 44325, United States.
authors.forename: Chongwen
authors.identifier: http://orcid.org/0000-0003-0726-3471
authors.initials: C
authors.lastname: Huang
authors.affiliation: Department of Polymer Engineering, College of Polymer Science and Polymer Engineering, The University of Akron , Akron, Ohio 44325, United States.
authors.forename: R A
authors.identifier: http://orcid.org/0000-0002-5700-6871
authors.initials: RA
authors.lastname: Weiss
authors.affiliation: Department of Polymer Engineering, College of Polymer Science and Polymer Engineering, The University of Akron , Akron, Ohio 44325, United States.|State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, P. R. China.
authors.forename: Xiong
authors.identifier: http://orcid.org/0000-0001-6525-3824
authors.initials: X
authors.lastname: Gong
keywords: charge carrier recombination; charge transport; interfacial modification; inverted polymer solar cells; ionomer