Article

Excited-state and photoelectrochemical behavior of pyrene-linked phenyleneethynylene oligomer.

Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.
The Journal of Physical Chemistry B (Impact Factor: 3.61). 11/2008; 112(46):14539-47. DOI: 10.1021/jp805878c
Source: PubMed

ABSTRACT An oligophenyleneethynylene (OPE), 1,4-bis(phenyleneethynyl)-2,5-bis(hexyloxy)benzene (2), is coupled with pyrene to extend the conjugation and allow its use as a light-harvesting molecule [Py-OPE (1)]. The absorption and emission maxima of 1 are red-shifted compared to those of 2. Similar differences in the singlet and triplet excited-state properties are evident. The fluorescence yield of 2 in toluene is 0.53, which is slightly less than the value for the parent OPE (2) of 0.66. The excited singlet and triplet of 1 as characterized from transient absorption spectroscopy exhibit lifetimes of 1.07 ns and 4.0 micros, respectively, in toluene. When 1 was cast as a film on a glass electrode (OTE) and excited with a 387-nm laser pulse, we observed the formation of excitons that decayed within a few picoseconds. When 1 was cast as a film on a SnO2-modified conducting glass electrode (OTE/SnO2), a small fraction of excitons dissociated to produce a long-lived charge-separated state. The role of the SnO2 interface in promoting charge separation was inferred from the photoelectrochemical measurements. Under visible light excitation, the OTE/SnO2 electrode was capable of generating photocurrent (approximately 0.25 mA/cm2) with an incident photon conversion efficiency (IPCE) of approximately 6%.

0 Bookmarks
 · 
66 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The study of interfacial charge-transfer processes (sensitization) of a dye bound to large-bandgap nanostructured metal oxide semiconductors, including TiO(2), ZnO, and SnO(2), is continuing to attract interest in various areas of renewable energy, especially for the development of dye-sensitized solar cells (DSSCs). The scope of this Review is to describe how selected model sensitizers prepared from organic polyaromatic hydrocarbons have been used over the past 15 years to elucidate, through a variety of techniques, fundamental aspects of heterogeneous charge transfer at the surface of a semiconductor. This Review does not focus on the most recent or efficient dyes, but rather on how model dyes prepared from aromatic hydrocarbons have been used, over time, in key fundamental studies of heterogeneous charge transfer. In particular, we describe model chromophores prepared from anthracene, pyrene, perylene, and azulene. As the level of complexity of the model dye-bridge-anchor group compounds has increased, the understanding of some aspects of very complex charge transfer events has improved. The knowledge acquired from the study of the described model dyes is of importance not only for DSSC development but also to other fields of science for which electronic processes at the molecule/semiconductor interface are relevant.
    ChemSusChem 02/2010; 3(4):410-28. · 7.48 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Organic soluble DNA bearing two different fluorophores in the side chain was prepared by reacting purified DNA with the cationic molecules 9-(12-bromododecyl)-9H-carbazole and (E)-1-(4-(12-bromododecyloxy)styryl)pyrene in water. Two homopolymers (CzDNA and PyDNA) and random copolymers (CzDNA-co-PyDNA) were prepared successfully. The absorption and photoluminescence (PL) behavior of CzDNA-co-PyDNA with pyrene derivative concentrations was investigated. As reference, we employed a guest-host system and polymer blends using DNA homopolymers. The Förster energy transfer process was investigated in three different DNA systems. The DNA copolymer system showed much better energy transfer efficiency than the other DNA systems. The copolymers were mixed with 2-{2-[2-(4-diethylamino-phenyl)-vinyl]-6-methyl-pyran-4-ylidene}-malononitrile (DCM) at an optimum concentration. At low DCM concentration (0.3 wt %), undesired emissions were observed due to an incomplete energy transfer process from excited pyrene moieties. At high DCM concentration (5.0 wt %), red emissions were predominant; this is attributed to an efficient Förster energy transfer process. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5416–5425, 2009
    Journal of Polymer Science Part A Polymer Chemistry 01/2009; 47(20):5416-5425. · 3.54 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Two pyrene-OPV-Fullerene triads were synthesized by a Williamson alkylation of [6,6] diphenolmethanofullerene with chlorobenzyl-OPV-pyrene oligomers. Molecular structure of all compounds was characterized by H and C NMR, FTIR, UV-Vis, fluorescence spectroscopy, and confirmed by electron impact, electrospray or FAB+ mass spectrometry and elemental analysis. The optical properties in chloroform solution indicate that triads increase the molar absorptivity compared to methanophenylfullerene, revealing interesting light harvesting properties.
    Fullerenes Nanotubes and Carbon Nanostructures - FULLER NANOTUB CARBON NANOSTR. 01/2012; 20(3):249-265.