@article{02696eaa90154cf4b38ab577925b44d1,
title = "Printing 2D Conjugated Polymer Monolayers and Their Distinct Electronic Properties",
abstract = "Recently, 2D monolayer films of conjugated polymers have gained increasing attention owing to the preeminence of 2D inorganic films that exhibit unique optoelectronic and mechanical properties compared to their bulk analogs. Despite numerous efforts, crystallization of semiconducting polymers into highly ordered 2D monolayer films still remains challenging. Herein, a dynamic-template-assisted meniscus-guided coating is utilized to fabricate continuous, highly ordered 2D monolayer films of conjugated polymers over a centimeter scale with enhanced backbone π–π stacking. In contrast, monolayer films printed on solid substrates confer upon the 1D fiber networks strong alkyl side-chain stacking at the expense of backbone packing. From single-layers to multilayers, the polymer π-stacks change from edge-on to bimodal orientation as the film thickness reaches ≈20 nm. Spectroscopic and cyclic voltammetry analysis reveals an abrupt increase in J-aggregation and absorption coefficient and a decrease in bandgap and highest occupied molecular orbital level until critical thickness, possibly arising from the straightened polymer backbone. This is corroborated by an abrupt increase in hole mobility with film thickness, reaching a maximum of 0.7 cm2 V−1 s−1 near the critical thickness. Finally, fabrication of chemical sensors incorporating polymer films of various thicknesses is demonstrated, and an ultrahigh sensitivity of the ≈7 nm thick ultrathin film (bilayers) to 1 ppb ammonia is shown.",
keywords = "2D, conjugated polymers, dynamic template, monolayers, morphology, organic electronics, printing, transistors",
author = "Prapti Kafle and Fengjiao Zhang and Schorr, {Noah B.} and Huang, {Kai Yu} and Joaqu{\'i}n Rodr{\'i}guez-L{\'o}pez and Ying Diao",
note = "Funding Information: This research was primarily supported by the NSF MRSEC: Illinois Materials Research Center under grant number DMR 17‐20633. P.K. acknowledges partial support from American Association of University Women (AAUW) International fellowship. Y.D. and K.‐Y. H. were partially supported by NSF CAREER award under grant number NSF DMR 18‐47828. Y.D. acknowledges partial support from JITRI International Fellowship. Part of the experiments of this research was conducted in Frederick Seitz Materials Research Laboratory Center Facilities, University of Illinois. This research used facilities of the Advanced Photon Source, a U.S Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contrast No. DE‐AC02‐06CH11357. The authors are grateful to beamline scientist Joseph W. Strazalka of Advanced Photon Source, Argonne National Laboratory for facilitating the GIXD measurements. Funding Information: This research was primarily supported by the NSF MRSEC: Illinois Materials Research Center under grant number DMR 17-20633. P.K. acknowledges partial support from American Association of University Women (AAUW) International fellowship. Y.D. and K.-Y. H. were partially supported by NSF CAREER award under grant number NSF DMR 18-47828. Y.D. acknowledges partial support from JITRI International Fellowship. Part of the experiments of this research was conducted in Frederick Seitz Materials Research Laboratory Center Facilities, University of Illinois. This research used facilities of the Advanced Photon Source, a U.S Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contrast No. DE-AC02-06CH11357. The authors are grateful to beamline scientist Joseph W. Strazalka of Advanced Photon Source, Argonne National Laboratory for facilitating the GIXD measurements. Publisher Copyright: {\textcopyright} 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim",
year = "2020",
month = mar,
day = "1",
doi = "10.1002/adfm.201909787",
language = "English (US)",
volume = "30",
journal = "Advanced Functional Materials",
issn = "1616-301X",
publisher = "Wiley-VCH",
number = "12",
}