title: Surpassing the Exciton Diffusion Limit in Single-Walled Carbon Nanotube Sensitized Solar Cells.
abstract: Semiconducting single-walled carbon nanotube (s-SWNT) light sensitized devices, such as infrared photodetectors and solar cells, have recently been widely reported. Despite their excellent individual electrical properties, efficient carrier transport from one carbon nanotube to another remains a fundamental challenge. Specifically, photovoltaic devices with active layers made from s-SWNTs have suffered from low efficiencies caused by three main challenges: the overwhelming presence of high-bandgap polymers in the films, the weak bandgap offset between the LUMO of the s-SWNTs and the acceptor C60, and the limited exciton diffusion length from one SWNT to another of around 5 nm that limits the carrier extraction efficiency. Herein, we employ a combination of processing and device architecture design strategies to address each of these transport challenges and fabricate photovoltaic devices with s-SWNT films well beyond the exciton diffusion limit of 5 nm. While our solution processing method minimizes the presence of undesired polymers in our active films, our interfacial designs led to a significant increase in current generation with the addition of a highly doped C60layer (n-doped C60), resulting in increased carrier separation efficiency from the s-SWNTs films. We create a dense interconnected nanoporous mesh of s-SWNTs using solution shearing and infiltrate it with the acceptor C60. Thus, our final engineered bulk heterojunction allows carriers from deep within to be extracted by the C60registering a 10-fold improvement in performance from our preliminary structures.
authors.affiliation: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Ghada I
authors.identifier: 0000-0002-0338-8472
authors.initials: GI
authors.lastname: Koleilat
authors.affiliation: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Vosgueritchian
authors.affiliation: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Ting
authors.identifier: 0000-0001-8190-9483
authors.initials: T
authors.lastname: Lei
authors.affiliation: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Debora W
authors.initials: DW
authors.lastname: Lin
authors.affiliation: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Franziska
authors.initials: F
authors.lastname: Lissel
authors.affiliation: School of Materials Science and Engineering, University of Science and Technology Beijing , Beijing 100083, People's Republic of China.
authors.forename: Pei
authors.identifier: 0000-0002-3300-5241
authors.initials: P
authors.lastname: Lin
authors.affiliation: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: John W F
authors.initials: JW
authors.lastname: To
authors.affiliation: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Tian
authors.initials: T
authors.lastname: Xie
authors.affiliation: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Kemar
authors.initials: K
authors.lastname: England
authors.affiliation: School of Materials Science and Engineering, University of Science and Technology Beijing , Beijing 100083, People's Republic of China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Zhenan
authors.initials: Z
authors.lastname: Bao
keywords: diffusion length; n-doped C60; nanoporous matrix; single-walled carbon nanotubes; solution shearing