@article{6653e2834d564dfd9436e06e6368250d,
title = "Multiphoton Microscopy of π-Conjugated Copolymers and Copolymer/Fullerene Blends for Organic Photovoltaic Applications",
abstract = "Organic photovoltaic (OPV) cells based on π-conjugated copolymer/fullerene blends are devices with the highest power conversion efficiencies within the class of organic semiconductors. Although a number of image microscopies have been applied to films of π-conjugated copolymers and their fullerene blends, seldom have they been able to detect microscopic defects in the blend films. We have applied multiphoton microscopy (MPM) using a 65 fs laser at 1.56 μm for spectroscopy and mapping of films of various π-conjugated copolymers and their fullerene blends. All pristine copolymer films have shown third harmonic generation (THG) and two-photon or three-photon photoluminescence that could be used for mapping the films with micrometer spatial resolution. Since the fullerenes have much weaker THG efficiency than those of the copolymers, we could readily map the copolymer/fullerene blend films that showed interpenetrating micron-sized grains of the two constituents. In addition, we also found second harmonic generation from various micron-sized defects in the films that are formed during film deposition or light illumination at ambient conditions, which do not possess inversion symmetry. The MPM method is therefore beneficial for organic films and devices for investigating the properties and growth of copolymer/fullerene blends for OPV applications.",
keywords = "MPM method, OPV cells, THG efficiency, copolymer/fullerene blends",
author = "Vardeny, {Shai R.} and Sangita Baniya and Benjamin Cromey and Khanh Kieu and Nasser Peyghambarian and Vardeny, {Z. Valy}",
note = "Funding Information: The work at the University of Utah was supported by the AFOSR grant FA9550-16-1-0207; the work at the University of Arizona was supported in part by the Space Exploration and Optical Solutions Technology Research Initiative Fund. Support for the multiphoton microscope work came from a National Science Foundation Graduate Research Fellowship under DGE-1143953 and NSF ECCS under Grant #1610048. We are grateful to Prof. Wei You for supplying the PBnDT-FTAZ powder. SEM and AFM measurements were performed at the Surface Analysis Laboratory of the University of Utah. All Multimode AFM images and data were collected in the W.M. Keck Center for nanoscale imaging in the Department of Chemistry and Biochemistry at the University of Arizona. This instrument purchase was supported by the Arizona Technology and Research Initiative Fund (A.R.S.§15-1648). Funding Information: The work at the University of Utah was supported by the AFOSR grant FA9550-16-1-0207; the work at the University of Arizona was supported in part by the Space Exploration and Optical Solutions Technology Research Initiative Fund. Support for the multiphoton microscope work came from a National Science Foundation Graduate Research Fellowship under DGE-1143953 and NSF ECCS under Grant #1610048. We are grateful to Prof. Wei You for supplying the PBnDT-FTAZ powder. SEM and AFM measurements were performed at the Surface Analysis Laboratory of the University of Utah. All Multimode AFM images and data were collected in the W.M. Keck Center for nanoscale imaging in the Department of Chemistry and Biochemistry at the University of Arizona. This instrument purchase was supported by the Arizona Technology and Research Initiative Fund (A.R.S.15-1648). Publisher Copyright: {\textcopyright} 2018 American Chemical Society.",
year = "2018",
month = sep,
day = "19",
doi = "10.1021/acsami.8b11378",
language = "English (US)",
volume = "10",
pages = "31813--31823",
journal = "ACS applied materials & interfaces",
issn = "1944-8244",
publisher = "American Chemical Society",
number = "37",
}