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Strategy for Enhancing the Dielectric Constant of Organic Semiconductors Without Sacrificing Charge Carrier Mobility and Solubility
Author(s) -
Torabi Solmaz,
Jahani Fatemeh,
Van Severen Ineke,
Kanimozhi Catherine,
Patil Satish,
Havenith Remco W. A.,
Chiechi Ryan C.,
Lutsen Laurence,
Vanderzande Dirk J. M.,
Cleij Thomas J.,
Hummelen Jan C.,
Koster L. Jan Anton
Publication year - 2015
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201402244
Subject(s) - materials science , organic semiconductor , electron mobility , organic solar cell , solubility , side chain , dielectric , polymer , semiconductor , charge carrier , exciton , band gap , triethylene glycol , fullerene , chemical physics , photochemistry , optoelectronics , polymer chemistry , organic chemistry , condensed matter physics , chemistry , physics , composite material
Current organic semiconductors for organic photovoltaics (OPV) have relative dielectric constants (relative permittivities, ε r ) in the range of 2–4. As a consequence, Coulombically bound electron‐hole pairs (excitons) are produced upon absorption of light, giving rise to limited power conversion efficiencies. We introduce a strategy to enhance ε r of well‐known donors and acceptors without breaking conjugation, degrading charge carrier mobility or altering the transport gap. The ability of ethylene glycol (EG) repeating units to rapidly reorient their dipoles with the charge redistributions in the environment was proven via density functional theory (DFT) calculations. Fullerene derivatives functionalized with triethylene glycol side chains were studied for the enhancement of ε r together with poly( p ‐phenylene vinylene) and diketopyrrolopyrrole based polymers functionalized with similar side chains. The polymers showed a doubling of ε r with respect to their reference polymers in identical backbone. Fullerene derivatives presented enhancements up to 6 compared with phenyl‐C 61 ‐butyric acid methyl ester (PCBM) as the reference. Importantly, the applied modifications did not affect the mobility of electrons and holes and provided excellent solubility in common organic solvents.