title: Efficient Vacuum-Deposited Ternary Organic Solar Cells with Broad Absorption, Energy Transfer, and Enhanced Hole Mobility.
abstract: The use of multiple donors in an active layer is an effective way to boost the efficiency of organic solar cells by broadening their absorption window. Here, we report an efficient vacuum-deposited ternary organic photovoltaic (OPV) using two donors, 2-((2-(5-(4-(diphenylamino)phenyl)thieno[3,2-b]thiophen-2-yl)thiazol-5-yl)methylene)malononitrile (DTTz) for visible absorption and 2-((7-(5-(dip-tolylamino)thiophen-2-yl)benzo[c]-[1,2,5]thiadiazol-4-yl)methylene)malononitrile (DTDCTB) for near-infrared absorption, codeposited with C70 in the ternary layer. The ternary device achieved a power conversion efficiency of 8.02%, which is 23% higher than that of binary OPVs. This enhancement is the result of incorporating two donors with complementary absorption covering wavelengths of 350 to 900 nm with higher hole mobility in the ternary layer than that of binary layers consisting of one donor and C70, combined with energy transfer from the donor with lower hole mobility (DTTz) to that with higher mobility (DTDCTB). This structure fulfills all the requirements for efficient ternary OPVs.
authors.affiliation: Department of Materials Science and Engineering, Seoul National University , Seoul 151-744, South Korea.
authors.forename: Hyun-Sub
authors.initials: HS
authors.lastname: Shim
authors.affiliation: Department of Materials Science and Engineering, Seoul National University , Seoul 151-744, South Korea.
authors.forename: Chang-Ki
authors.initials: CK
authors.lastname: Moon
authors.affiliation: Intellectual Textile System Research Center (ITRC) and RIAM School of Materials Science and Engineering, College of Engineering, Seoul National University , Daehakro 1, Kwanakgu, Seoul, 151-744, South Korea.
authors.forename: Jihun
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Chemistry, National Taiwan University , Taipei 10617, Taiwan.
authors.forename: Chun-Kai
authors.initials: CK
authors.lastname: Wang
authors.affiliation: Department of Materials Science and Engineering, Seoul National University , Seoul 151-744, South Korea.
authors.forename: Bomi
authors.initials: B
authors.lastname: Sim
authors.affiliation: Department of Chemistry, National Taiwan University , Taipei 10617, Taiwan.
authors.forename: Francis
authors.initials: F
authors.lastname: Lin
authors.affiliation: Department of Chemistry, National Taiwan University , Taipei 10617, Taiwan.
authors.forename: Ken-Tsung
authors.initials: KT
authors.lastname: Wong
authors.affiliation: Intellectual Textile System Research Center (ITRC) and RIAM School of Materials Science and Engineering, College of Engineering, Seoul National University , Daehakro 1, Kwanakgu, Seoul, 151-744, South Korea.
authors.forename: Yongsok
authors.initials: Y
authors.lastname: Seo
authors.affiliation: Department of Materials Science and Engineering, Seoul National University , Seoul 151-744, South Korea.
authors.forename: Jang-Joo
authors.initials: JJ
authors.lastname: Kim
keywords: broad absorption; cascade energy levels; energy transfer; ternary layer; vacuum deposition