Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 28Citation - Scopus: 30P3HT-graphene bilayer electrode for Schottky junction photodetectors(IOP Publishing Ltd., 2018) Aydın, Hasan; Kalkan, Sırrı Batuhan; Varlıklı, Canan; Çelebi, CemWe have investigated the effect of a poly (3-hexylthiophene-2.5-diyl)(P3HT)-graphene bilayer electrode on the photoresponsivity characteristics of Si-based Schottky photodetectors. P3HT, which is known to be an electron donor and absorb light in the visible spectrum, was placed on CVD grown graphene by dip-coating method. The results of the UV-vis and Raman spectroscopy measurements have been evaluated to confirm the optical and electronic modification of graphene by the P3HT thin film. Current-voltage measurements of graphene/Si and P3HT-graphene/Si revealed rectification behavior confirming a Schottky junction formation at the graphene/Si interface. Time-resolved photocurrent spectroscopy measurements showed the devices had excellent durability and a fast response speed. We found that the maximum spectral photoresponsivity of the P3HT-graphene/Si photodetector increased more than three orders of magnitude compared to that of the bare graphene/Si photodetector. The observed increment in the photoresponsivity of the P3HT-graphene/Si samples was attributed to the charge transfer doping from P3HT to graphene within the spectral range between near-ultraviolet and near-infrared. Furthermore, the P3HT-graphene electrode was found to improve the specific detectivity and noise equivalent power of graphene/Si photodetectors. The obtained results showed that the P3HT-graphene bilayer electrodes significantly improved the photoresponsivity characteristics of our samples and thus can be used as a functional component in Si-based optoelectronic device applications.Article Citation - WoS: 16Citation - Scopus: 19N,n-Dialkylaniline Tetraethynylethenes: a New Class of Chromophores Possessing an Emitting Charge-Transfer State. Experimental and Computational Studies(John Wiley and Sons Inc., 2001) Gobbi, Luca; Elmacı, Nuran; Lüthi, Hans Peter; Diederich, FrançoisThe photophysical properties of N,N-dimethylaniline- (DMA) substituted tetraethynylethene (TEE; 3,4-diethynylhex-3-ene-1,5-diyne) and related derivatives were investigated in a joint experimental and computational study. Measurements of the electronic emission spectra showed that these novel chromophores display a dual fluorescence which strongly depends on solvent polarity. Computational studies suggest that the twisted intramolecular charge-transfer state (TICT) model offers a possible explanation for the experimentally observed dual fluorescence. Time-dependent density functional calculations revealed that the initial excited state reached upon photoirradiation relaxes to a lower-energy TICT state in which either the dimethylamino group is twisted into an orthogonal position with respect to the remaining planar arylated TEE moiety or the entire DMA donor group takes an orthogonal orientation with respect to the rigid, planar TEE acceptor moiety. For the compounds investigated, the charge-transfer state responsible for the strongly solvent-dependent luminescence is directly connected with the initial excited state, namely, no crossing of states is involved.