@article{49bef7ff1eb046f6838165078296e197,
title = "Controlled n-Doping of Naphthalene-Diimide-Based 2D Polymers",
abstract = "2D polymers (2DPs) are promising as structurally well-defined, permanently porous, organic semiconductors. However, 2DPs are nearly always isolated as closed shell organic species with limited charge carriers, which leads to low bulk conductivities. Here, the bulk conductivity of two naphthalene diimide (NDI)-containing 2DP semiconductors is enhanced by controllably n-doping the NDI units using cobaltocene (CoCp2). Optical and transient microwave spectroscopy reveal that both as-prepared NDI-containing 2DPs are semiconducting with sub-2 eV optical bandgaps and photoexcited charge-carrier lifetimes of tens of nanoseconds. Following reduction with CoCp2, both 2DPs largely retain their periodic structures and exhibit optical and electron-spin resonance spectroscopic features consistent with the presence of NDI-radical anions. While the native NDI-based 2DPs are electronically insulating, maximum bulk conductivities of >10−4S cm−1 are achieved by substoichiometric levels of n-doping. Density functional theory calculations show that the strongest electronic couplings in these 2DPs exist in the out-of-plane (π-stacking) crystallographic directions, which indicates that cross-plane electronic transport through NDI stacks is primarily responsible for the observed electronic conductivity. Taken together, the controlled molecular doping is a useful approach to access structurally well-defined, paramagnetic, 2DP n-type semiconductors with measurable bulk electronic conductivities of interest for electronic or spintronic devices.",
keywords = "2D polymers, conductive polymers, n-type molecular doping, organic semiconductors",
author = "Evans, {Austin M.} and Collins, {Kelsey A.} and Sangni Xun and Allen, {Taylor G.} and Samik Jhulki and Ioannina Castano and Smith, {Hannah L.} and Strauss, {Michael J.} and Oanta, {Alexander K.} and Lujia Liu and Lei Sun and Reid, {Obadiah G.} and Gjergji Sini and Danilo Puggioni and Rondinelli, {James M.} and Tijana Rajh and Gianneschi, {Nathan C.} and Antoine Kahn and Freedman, {Danna E.} and Hong Li and Stephen Barlow and Garry Rumbles and Br{\'e}das, {Jean Luc} and Marder, {Seth R.} and Dichtel, {William R.}",
note = "Funding Information: The Army Research Office is thanked for a Multidisciplinary University Research Initiatives (MURI) award under grant W911NF-15-1-0447, which supported the preparation of electroactive 2DPs, optical characterization, and study using density functional theory. The Department of Energy grant DE-SC0019356 is thanked for supporting efforts at controlled molecular doping, including the investigation of charge transport, electronic structure, and paramagnetic behavior. A.M.E. (DGE-1324585), K.A.C. (DGE-1842165), I.C. (DGE-11842165), and M.J.S. (DGE-11842165) were supported by the National Science Foundation Graduate Research Fellowship. S.J. thanks the United States-India Educational Foundation (USIEF, India) and the Institute of International Education (IIE, USA) for a Fulbright-Nehru Postdoctoral Fellowship (grant no. 2266/FNPDR/2017). Work in Princeton was supported in part by a grant of the National Science Foundation (DMR-1807797) (H.L.S. and A.K.) and by a National Science Foundation Graduate Research Fellowship (DGE-1656466) (H.L.S.). This study made use of the IMSERC and EPIC at Northwestern University, both of which have received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF NNCI-1542205 and NSF ECCS1542205, respectively), the Materials Research Science and Engineering Center (National Science Foundation DMR-1720139), the State of Illinois, and the International Institute for Nanotechnology (IIN). Portions of this work were performed at the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) located at Sector 5 and Sector 8 of the Advanced Photon Source (APS). DND-CAT was supported by Northwestern University, E.I. DuPont de Nemours & Co., and the Dow Chemical Company. This research used resources of the Advanced Photon Source and Center for Nanoscale Materials, both U.S. Department of Energy (DOE) Office of Science User Facilities operated for the DOE Office of Science by Argonne National Laboratory under contract DE-AC02-06CH11357, and the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Resources at the Advanced Photon Source were funded by National Science Foundation under award 0960140. This work was authored by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding for microwave measurements was provided by Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Biosciences, and Geosciences. The computational work was supported in part by a grant of computer time from the DOD High Performance Computing Modernization Program. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes. T.G.A and G.R. thank Obadiah Reid for helpful discussions regarding microwave measurements. Publisher Copyright: {\textcopyright} 2022 Wiley-VCH GmbH.",
year = "2022",
month = jun,
day = "2",
doi = "10.1002/adma.202101932",
language = "English (US)",
volume = "34",
journal = "Advanced Materials",
issn = "0935-9648",
publisher = "Wiley-VCH Verlag",
number = "22",
}