Tuning the electronic coupling in a low-bandgap donor-acceptor copolymer via the placement of side-chains

Journal Article · Mon Mar 21 04:00:00 EDT 2011 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3562936· OSTI ID:21560059

Oberhumer, Philipp M; Huang, Ya-Shih; Massip, Sylvain; Albert-Seifried, Sebastian; Greenham, Neil C; Hodgkiss, Justin M; Friend, Richard H ^[1]; James, David T; Kim, Ji-Seon ^[2]; Guoli, Tu; Huck, Wilhelm T. S. ^[3]; Beljonne, David; Cornil, Jerome ^[4]

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1. Cavendish Laboratory, J J Thomson Avenue, Cambridge CB3 0HE (United Kingdom)
2. Blackett Laboratory, Imperial College, London SW7 2AZ (United Kingdom)
3. Melville Laboratory for Polymer Synthesis, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)
4. Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc, 20, 7000 Mons (Belgium)

We present a spectroscopic and theoretical investigation of the effect of the presence and position of hexyl side-chains in the novel low-bandgap alternating donor-acceptor copolymer poly[bis-N,N-(4-octylphenyl)-bis-N,N-phenyl-1, 4-phenylenediamine-alt-5,5'-4',7',-di-2-thienyl-2',1',3'-benzothiadiazole] (T8TBT). We use electronic absorption and Raman spectroscopic measurements supported by calculations of chain conformation, electronic transitions, and Raman modes. Using these tools, we find that sterically demanding side-chain configurations induce twisting in the electronic acceptor unit and reduce the electronic interaction with the donor. This leads to a blue-shifted and weakened (partial) charge-transfer absorption band together with a higher photoluminescence efficiency. On the other hand, sterically relaxed side-chain configurations promote coupling between donor and acceptor units and exhibit enhanced absorption at the expense of luminescence efficiency. The possibility of tuning the donor-acceptor character of conjugated polymers by varying the placement of side-chains has very important ramifications for light emitting diode, Laser, display, and photovoltaic device optimization.

• OSTI ID: 21560059
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 11 Vol. 134; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION
CHARGE EXCHANGE
CONFIGURATION
COPOLYMERS
EFFICIENCY
ELECTRONS
ELEMENTARY PARTICLES
EMISSION
ENERGY GAP
FERMIONS
INTERACTIONS
LASERS
LEPTONS
LIGHT EMITTING DIODES
LUMINESCENCE
OPTIMIZATION
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PHOTOELECTRIC EFFECT
PHOTOLUMINESCENCE
PHOTON EMISSION
PHOTOVOLTAIC EFFECT
POLYMERS
RAMAN SPECTRA
SEMICONDUCTOR DEVICES
SEMICONDUCTOR DIODES
SORPTION
SPECTRA
SPECTRAL SHIFT