Abstract
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.
| Original language | English |
|---|---|
| Pages (from-to) | 5633-5640 |
| Number of pages | 8 |
| Journal | Journal of Physical Chemistry Letters |
| Volume | 14 |
| Issue number | 24 |
| DOIs | |
| State | Published - Jun 22 2023 |
Bibliographical note
Publisher Copyright:© 2023 American Chemical Society.
Funding
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. 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
| Funders | Funder number |
|---|---|
| Center for Soft Photo Electro Chemical Systems | |
| Department of Energy Office of Basic Energy Sciences | |
| U.S. Government | |
| National Science Foundation Arctic Social Science Program | 1849213 |
| National Science Foundation Arctic Social Science Program | |
| Office of Naval Research Naval Academy | N00014-20-1-2587 |
| Office of Naval Research Naval Academy | |
| U.S. Department of Energy EPSCoR | DE-AC36-08GO28308 |
| U.S. Department of Energy EPSCoR | |
| Office of Science Programs | |
| DOE Basic Energy Sciences | DMR-1729737, DMR-1807797/2216857, DE-SC0023411 |
| DOE Basic Energy Sciences | |
| National Renewable Energy Laboratory | |
| Laboratory Directed Research and Development | |
| Division of Materials Sciences and Engineering | -SC0012458 |
| Division of Materials Sciences and Engineering | |
| Deutsche Forschungsgemeinschaft | 182087777-SFB 951, 239543752 |
| Deutsche Forschungsgemeinschaft |
ASJC Scopus subject areas
- General Materials Science
- Physical and Theoretical Chemistry