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Png RQ, Ang MC, Teo MH, Choo KK, Tang CG, Belaineh D, Chua LL, Ho PK. Madelung and Hubbard interactions in polaron band model of doped organic semiconductors. Nat Commun 2016; 7:11948. [PMID: 27582355 PMCID: PMC5025745 DOI: 10.1038/ncomms11948] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 05/17/2016] [Indexed: 11/09/2022] Open
Abstract
The standard polaron band model of doped organic semiconductors predicts that density-of-states shift into the π-π* gap to give a partially filled polaron band that pins the Fermi level. This picture neglects both Madelung and Hubbard interactions. Here we show using ultrahigh workfunction hole-doped model triarylamine-fluorene copolymers that Hubbard interaction strongly splits the singly-occupied molecular orbital from its empty counterpart, while Madelung (Coulomb) interactions with counter-anions and other carriers markedly shift energies of the frontier orbitals. These interactions lower the singly-occupied molecular orbital band below the valence band edge and give rise to an empty low-lying counterpart band. The Fermi level, and hence workfunction, is determined by conjunction of the bottom edge of this empty band and the top edge of the valence band. Calculations are consistent with the observed Fermi-level downshift with counter-anion size and the observed dependence of workfunction on doping level in the strongly doped regime.
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Affiliation(s)
- Rui-Qi Png
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117550, Singapore
- Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, 7 Engineering Drive 1, Singapore S117574, Singapore
| | - Mervin C.Y. Ang
- Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, 7 Engineering Drive 1, Singapore S117574, Singapore
- Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, Singapore S117552, Singapore
| | - Meng-How Teo
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117550, Singapore
| | - Kim-Kian Choo
- Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, Singapore S117552, Singapore
| | - Cindy Guanyu Tang
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117550, Singapore
- Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, 7 Engineering Drive 1, Singapore S117574, Singapore
| | - Dagmawi Belaineh
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117550, Singapore
| | - Lay-Lay Chua
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117550, Singapore
- Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, 7 Engineering Drive 1, Singapore S117574, Singapore
- Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, Singapore S117552, Singapore
| | - Peter K.H. Ho
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117550, Singapore
- Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, 7 Engineering Drive 1, Singapore S117574, Singapore
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Sancho-García JC, Foden CL, Grizzi I, Greczynski G, de Jong MP, Salaneck WR, Brédas JL, Cornil J. Joint Theoretical and Experimental Characterization of the Structural and Electronic Properties of Poly(dioctylfluorene-alt-N-butylphenyl diphenylamine). J Phys Chem B 2004. [DOI: 10.1021/jp049631w] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J. C. Sancho-García
- Laboratory for Chemistry of Novel Materials, Center for Research in Molecular Electronics and Photonics, University of Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium, Cambridge Display Technology, Greenwich House, Madingley Rise, Madingley Road, Cambridge CB3 0TX, United Kingdom, Thin Films Electronics, Westmansgatan 27, S-582 16 Linköping, Sweden, Department of Physics, IFM, Linköping University, S-581 83 Linköping, Sweden, and School of Chemistry and Biochemistry, Georgia Institute of Technology,
| | - C. L. Foden
- Laboratory for Chemistry of Novel Materials, Center for Research in Molecular Electronics and Photonics, University of Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium, Cambridge Display Technology, Greenwich House, Madingley Rise, Madingley Road, Cambridge CB3 0TX, United Kingdom, Thin Films Electronics, Westmansgatan 27, S-582 16 Linköping, Sweden, Department of Physics, IFM, Linköping University, S-581 83 Linköping, Sweden, and School of Chemistry and Biochemistry, Georgia Institute of Technology,
| | - I. Grizzi
- Laboratory for Chemistry of Novel Materials, Center for Research in Molecular Electronics and Photonics, University of Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium, Cambridge Display Technology, Greenwich House, Madingley Rise, Madingley Road, Cambridge CB3 0TX, United Kingdom, Thin Films Electronics, Westmansgatan 27, S-582 16 Linköping, Sweden, Department of Physics, IFM, Linköping University, S-581 83 Linköping, Sweden, and School of Chemistry and Biochemistry, Georgia Institute of Technology,
| | - G. Greczynski
- Laboratory for Chemistry of Novel Materials, Center for Research in Molecular Electronics and Photonics, University of Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium, Cambridge Display Technology, Greenwich House, Madingley Rise, Madingley Road, Cambridge CB3 0TX, United Kingdom, Thin Films Electronics, Westmansgatan 27, S-582 16 Linköping, Sweden, Department of Physics, IFM, Linköping University, S-581 83 Linköping, Sweden, and School of Chemistry and Biochemistry, Georgia Institute of Technology,
| | - M. P. de Jong
- Laboratory for Chemistry of Novel Materials, Center for Research in Molecular Electronics and Photonics, University of Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium, Cambridge Display Technology, Greenwich House, Madingley Rise, Madingley Road, Cambridge CB3 0TX, United Kingdom, Thin Films Electronics, Westmansgatan 27, S-582 16 Linköping, Sweden, Department of Physics, IFM, Linköping University, S-581 83 Linköping, Sweden, and School of Chemistry and Biochemistry, Georgia Institute of Technology,
| | - W. R. Salaneck
- Laboratory for Chemistry of Novel Materials, Center for Research in Molecular Electronics and Photonics, University of Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium, Cambridge Display Technology, Greenwich House, Madingley Rise, Madingley Road, Cambridge CB3 0TX, United Kingdom, Thin Films Electronics, Westmansgatan 27, S-582 16 Linköping, Sweden, Department of Physics, IFM, Linköping University, S-581 83 Linköping, Sweden, and School of Chemistry and Biochemistry, Georgia Institute of Technology,
| | - J. L. Brédas
- Laboratory for Chemistry of Novel Materials, Center for Research in Molecular Electronics and Photonics, University of Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium, Cambridge Display Technology, Greenwich House, Madingley Rise, Madingley Road, Cambridge CB3 0TX, United Kingdom, Thin Films Electronics, Westmansgatan 27, S-582 16 Linköping, Sweden, Department of Physics, IFM, Linköping University, S-581 83 Linköping, Sweden, and School of Chemistry and Biochemistry, Georgia Institute of Technology,
| | - J. Cornil
- Laboratory for Chemistry of Novel Materials, Center for Research in Molecular Electronics and Photonics, University of Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium, Cambridge Display Technology, Greenwich House, Madingley Rise, Madingley Road, Cambridge CB3 0TX, United Kingdom, Thin Films Electronics, Westmansgatan 27, S-582 16 Linköping, Sweden, Department of Physics, IFM, Linköping University, S-581 83 Linköping, Sweden, and School of Chemistry and Biochemistry, Georgia Institute of Technology,
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