TY - JOUR
T1 - Spectral Signatures of a Negative Polaron in a Doped Polymer Semiconductor
T2 - Energy Levels and Hubbard U Interactions
AU - Lungwitz, Dominique
AU - Joy, Syed
AU - Mansour, Ahmed E.
AU - Opitz, Andreas
AU - Karunasena, Chamikara
AU - Li, Hong
AU - Panjwani, Naitik A.
AU - Moudgil, Karttikay
AU - Tang, Kan
AU - Behrends, Jan
AU - Barlow, Stephen
AU - Marder, Seth R.
AU - Brédas, Jean Luc
AU - Graham, Kenneth
AU - Koch, Norbert
AU - Kahn, Antoine
N1 - Funding Information:
Work at Princeton University was supported in part by a grant from the Department of Energy Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award #DE-SC0012458. The work at University of Kentucky was supported by the National Science Foundation and under cooperative agreement No. 1849213. Work in Berlin was supported by the Deutsche Forschungsgemeinschaft (DFG) - project numbers 239543752 and 182087777-SFB 951. The work at Arizona was supported by the Center for Soft Photo Electro Chemical Systems, an Energy Frontier Research Center funded by DOE, Office of Science, BES under Award # DE-SC0023411 (theoretical calculations at DFT level). Work at Georgia Tech and Boulder was supported by the National Science Foundation (through DMR-1807797/2216857, through the DMREF program, DMR-1729737 and ONR (N00014-20-1-2587). This work was authored in part by the National Renewable Energy Laboratory (NREL), operated by the Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. The synthesis of (N-DMBI)2 was carried out as part of a Laboratory Directed Research and Development (LDRD) Program at NREL. 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.
Funding Information:
Work at Princeton University was supported in part by a grant from the Department of Energy Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award #DE-SC0012458. The work at University of Kentucky was supported by the National Science Foundation and under cooperative agreement No. 1849213. Work in Berlin was supported by the Deutsche Forschungsgemeinschaft (DFG) – project numbers 239543752 and 182087777-SFB 951. The work at Arizona was supported by the Center for Soft Photo Electro Chemical Systems, an Energy Frontier Research Center funded by DOE, Office of Science, BES under Award # DE-SC0023411 (theoretical calculations at DFT level). Work at Georgia Tech and Boulder was supported by the National Science Foundation (through DMR-1807797/2216857, through the DMREF program, DMR-1729737 and ONR (N00014-20-1-2587). This work was authored in part by the National Renewable Energy Laboratory (NREL), operated by the Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. The synthesis of (N-DMBI) was carried out as part of a Laboratory Directed Research and Development (LDRD) Program at NREL. 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. 2
Publisher Copyright:
© 2023 American Chemical Society.
PY - 2023/6/22
Y1 - 2023/6/22
N2 - The modern picture of negative charge carriers on conjugated polymers invokes the formation of a singly occupied (spin-up/spin-down) level within the polymer gap and a corresponding unoccupied level above the polymer conduction band edge. The energy splitting between these sublevels is related to on-site Coulomb interactions between electrons, commonly termed Hubbard U. However, spectral evidence for both sublevels and experimental access to the U value is still missing. Here, we provide evidence by n-doping the polymer P(NDI2OD-T2) with [RhCp*Cp]2, [N-DMBI]2, and cesium. Changes in the electronic structure after doping are studied with ultraviolet photoelectron and low-energy inverse photoemission spectroscopies (UPS, LEIPES). UPS data show an additional density of states (DOS) in the former empty polymer gap while LEIPES data show an additional DOS above the conduction band edge. These DOS are assigned to the singly occupied and unoccupied sublevels, allowing determination of a U value of ∼1 eV.
AB - The modern picture of negative charge carriers on conjugated polymers invokes the formation of a singly occupied (spin-up/spin-down) level within the polymer gap and a corresponding unoccupied level above the polymer conduction band edge. The energy splitting between these sublevels is related to on-site Coulomb interactions between electrons, commonly termed Hubbard U. However, spectral evidence for both sublevels and experimental access to the U value is still missing. Here, we provide evidence by n-doping the polymer P(NDI2OD-T2) with [RhCp*Cp]2, [N-DMBI]2, and cesium. Changes in the electronic structure after doping are studied with ultraviolet photoelectron and low-energy inverse photoemission spectroscopies (UPS, LEIPES). UPS data show an additional density of states (DOS) in the former empty polymer gap while LEIPES data show an additional DOS above the conduction band edge. These DOS are assigned to the singly occupied and unoccupied sublevels, allowing determination of a U value of ∼1 eV.
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U2 - 10.1021/acs.jpclett.3c01022
DO - 10.1021/acs.jpclett.3c01022
M3 - Article
C2 - 37310355
AN - SCOPUS:85163542889
SN - 1948-7185
VL - 14
SP - 5633
EP - 5640
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
IS - 24
ER -