title: Molecular helices as electron acceptors in high-performance bulk heterojunction solar cells.
abstract: Despite numerous organic semiconducting materials synthesized for organic photovoltaics in the past decade, fullerenes are widely used as electron acceptors in highly efficient bulk-heterojunction solar cells. None of the non-fullerene bulk heterojunction solar cells have achieved efficiencies as high as fullerene-based solar cells. Design principles for fullerene-free acceptors remain unclear in the field. Here we report examples of helical molecular semiconductors as electron acceptors that are on par with fullerene derivatives in efficient solar cells. We achieved an 8.3% power conversion efficiency in a solar cell, which is a record high for non-fullerene bulk heterojunctions. Femtosecond transient absorption spectroscopy revealed both electron and hole transfer processes at the donor-acceptor interfaces. Atomic force microscopy reveals a mesh-like network of acceptors with pores that are tens of nanometres in diameter for efficient exciton separation and charge transport. This study describes a new motif for designing highly efficient acceptors for organic solar cells.
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhong
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA.
authors.forename: M Tuan
authors.initials: MT
authors.lastname: Trinh
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA.|School of Chemical Engineering and Technology, Wuhan University of Science and Technology, Wuhan 430081, China.
authors.forename: Rongsheng
authors.initials: R
authors.lastname: Chen
authors.affiliation: Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Geoffrey E
authors.initials: GE
authors.lastname: Purdum
authors.affiliation: Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Petr P
authors.initials: PP
authors.lastname: Khlyabich
authors.affiliation: Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Melda
authors.initials: M
authors.lastname: Sezen
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA.
authors.forename: Seokjoon
authors.initials: S
authors.lastname: Oh
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA.
authors.forename: Haiming
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA.
authors.forename: Brandon
authors.initials: B
authors.lastname: Fowler
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA.
authors.forename: Boyuan
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York, New York 11973, USA.
authors.forename: Chang-Yong
authors.initials: CY
authors.lastname: Nam
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York, New York 11973, USA.
authors.forename: Matthew Y
authors.initials: MY
authors.lastname: Sfeir
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York, New York 11973, USA.
authors.forename: Charles T
authors.initials: CT
authors.lastname: Black
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Steigerwald
authors.affiliation: Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Yueh-Lin
authors.initials: YL
authors.lastname: Loo
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA.
authors.forename: Fay
authors.initials: F
authors.lastname: Ng
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA.
authors.forename: X-Y
authors.initials: XY
authors.lastname: Zhu
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA.
authors.forename: Colin
authors.initials: C
authors.lastname: Nuckolls
mesh_terms: D011211:Electric Power Supplies; D004583:Electrons; D007094:Imides / Q000737:chemistry / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D015394:Molecular Structure; D036103:Nanotechnology; D010569:Perylene / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D011108:Polymers / Q000737:chemistry / Q000378:metabolism*; D012666:Semiconductors; D012993:Solar Energy; D013057:Spectrum Analysis; D014961:X-Ray Diffraction
chemical_list: D007094:Imides; D011108:Polymers; C521332:perylenediimide; D010569:Perylene