Browsing by Subject "Photophysical properties"

Now showing 1 - 4 of 4

Open Access
Colloidal nanocrystals embedded in macrocrystals: methods and applications
(American Chemical Society, 2016) Adam, M.; Gaponik N.; Eychmüller A.; Erdem, T.; Soran-Erdem, Z.; Demir, Hilmi Volkan
Colloidal semiconductor nanocrystals have gained substantial interest as spectrally tunable and bright fluorophores for color conversion and enrichment solids. However, they suffer from limitations in processing their solutions as well as efficiency degradation in solid films. As a remedy, embedding them into crystalline host matrixes has stepped forward for superior photostability, thermal stability, and chemical durability while simultaneously sustaining high quantum yields. Here, we review three basic methods for loading the macrocrystals with nanocrystals, namely relatively slow direct embedding, as well as accelerated methods of vacuum-assisted and liquid-liquid diffusion-assisted crystallization. We discuss photophysical properties of the resulting composites and present their application in light-emitting diodes as well as their utilization for plasmonics and excitonics. Finally, we present a future outlook for the science and technology of these materials.
Open Access
Effect of chalcogens on electronic and photophysical properties of vinylene-based diketopyrrolopyrrole copolymers
(American Chemical Society, 2015) Dhar, J.; Mukhopadhay, T.; Yaacobi-Gross, N.; Anthopoulos, T. D.; Salzner, U.; Swaraj, S.; Patil, S.
Three vinylene linked diketopyrrolopyrrole based donor−acceptor (D−A) copolymers have been synthesized with phenyl, thienyl, and selenyl units as donors. Optical and electronic properties were investigated with UV−vis absorption spectroscopy, cyclic voltammetry, near edge X-ray absorption spectroscopy, organic field effect transistor (OFET) measurements, and density functional theory (DFT) calculations. Optical and electrochemical band gaps decrease in the order phenyl, thienyl, and selenyl. Only phenyl-based polymers are nonplanar, but the main contributor to the larger band gap is electronic, not structural effects. Thienyl and selenyl polymers exhibit ambipolar charge transport but with higher hole than electron mobility. Experimental and theoretical results predict the selenyl system to have the best transport properties, but OFET measurements prove the thienyl system to be superior with p-channel mobility as high as 0.1 cm2 V−1 s −1.
Open Access
The effect of cucurbit[n]uril on the solubility, morphology, and the photophysical properties of nonionic conjugated polymers in an aqueous medium
(2010) Tuncel, D.; Artar, M.; Hanay, S. B.
The effects of cucurbit[n]uril on the dissolution and the photophysical properties of nonionic conjugated polymers in water are described. For this purpose, a fluorine-based polymer, namely, poly[9,9-bis{6(N,N-dimethylamino) hexyl}fluorene-co-2,5-thienylene (PFT) was synthesized and characterized by spectroscopic techniques including 1D and 2D NMR, UV-vis, fluorescent spectroscopy, and matrix-assisted laser desorption mass spectrometry (MALDI-MS). For the first time, it was demonstrated that a nonionic conjugated polymer can be made soluble in water through an inclusion complex formation with CB8. The structure of the complex was elucidated by NMR experiments including 1H and selective 1D-NOESY. This complex emits green and is highly fluorescent with fluorescent quantum yield of 35%. In contrast, CB6 or water-soluble CB7 although they are chemically identical to CB8 do not have any effect on the dissolution and photophysical properties of PFT. By preparing a protonated version of PFT, the optical properties of PFT in methanol, protonated PFT and PFT@CB8 in water have been studied and compared. It was also observed that the morphology of the polymer PFT was affected by the presence of CB8. Thus CB8-assisted self-assembly of polymer chains leads to vesicles formation; these structures were characterized by DLS, AFM, SEM, and TEM fluorescent optical microscopy.
Open Access
Synthesis and investigation of singlet oxygen production efficiency of photosensitizers based on meso-phenyl-2,5-thienylene linked porphyrin oligomers and polymers
(Royal Society of Chemistry, 2015) Khan, R.; Idris, M.; Tuncel, D.
Three new Zn(ii)-, oligo- and poly(2,5-thienylene)-linked porphyrins, bearing multiple triethylene glycol (TEG) groups, on all meso aryl positions were synthesized via Stille and Suzuki coupling reactions and their photophysical properties as well as singlet oxygen generation efficiencies have been investigated to elucidate the possibility of their use as a photosensitizer for photodynamic therapy (PDT) and photodynamic inactivation of bacteria. © The Royal Society of Chemistry 2015.