Strategy for Enhancing the Dielectric Constant of Organic Semiconductors Without Sacrificing Charge Carrier Mobility and Solubility

Torabi, Solmaz and Jahani, Fatemeh and Van Severen, Ineke and Kanimozhi, Catherine and Patil, Satish and Havenith, Remco WA and Chiechi, Ryan C and Lutsen, Laurence and Vanderzande, Dirk JM and Cleij, Thomas J and Hummelen, Jan C and Koster, Jan Anton L (2015) Strategy for Enhancing the Dielectric Constant of Organic Semiconductors Without Sacrificing Charge Carrier Mobility and Solubility. In: ADVANCED FUNCTIONAL MATERIALS, 25 (1). pp. 150-157.

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Abstract

Current organic semiconductors for organic photovoltaics (OPV) have relative dielectric constants (relative permittivities, epsilon(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 epsilon(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 epsilon(r) together with poly(p-phenylene vinylene) and diketo-pyrrolopyrrole based polymers functionalized with similar side chains. The polymers showed a doubling of epsilon(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.

Item Type:	Journal Article
Publication:	ADVANCED FUNCTIONAL MATERIALS
Publisher:	WILEY-V C H VERLAG GMBH
Additional Information:	Copy right for this article belongs to the WILEY-V C H VERLAG GMBH, BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	06 Feb 2015 11:26
Last Modified:	06 Feb 2015 11:26
URI:	http://eprints.iisc.ac.in/id/eprint/50761

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