Third order nonlinear optical properties of phthalocyanines in the presence nanomaterials and in polymer thin films
- Authors: Britton, Jonathan , Durmus, Mahmut , Khene, Samson M , Chauke, Vongani , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241772 , vital:50968 , xlink:href="https://doi.org/10.1142/S108842461350003X"
- Description: Third order nonlinear optical properties were determined for phthalocyanine complexes 1–10 containing In, Ga and Zn central metals and tetra- or octa-substituted with benzyloxyphenoxy, phenoxy, tert-butylphenoxy and amino groups at peripheral or non-peripheral positions. The phthalocyanines were embedded in poly (methyl methacrylate) polymer in the presence of CdTe quantum dots. All complexes 1–10 were studied in the presence of CdTe quantum dots and embedded in poly (methyl methacrylate) to form thin films. Complex 3 tetrasubstituted with tert-butylphenoxy groups at non-peripheral positions was also studied in the presence of CdS, CdSe quantum dots, fullerenes, single walled carbon nanotubes. Third order nonlinear optical parameters generally increase for Pcs in the presence of CdTe quantum dots.
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- Date Issued: 2013
Ultrafast Photodynamics of the Indoline Dye D149 Adsorbed to Porous ZnO in Dye‐Sensitized Solar Cells
- Authors: Rohwer, Egmont , Richter, Christoph , Heming, Nadine , Strauch, Kerstin , Litwinski, Christian , Nyokong, Tebello , Schlettwein, Derck , Schwoerer, Heinrich
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242153 , vital:51006 , xlink:href="https://doi.org/10.1002/cphc.201200715"
- Description: We investigate the ultrafast dynamics of the photoinduced electron transfer between surface-adsorbed indoline D149 dye and porous ZnO as used in the working electrodes of dye-sensitized solar cells. Transient absorption spectroscopy was conducted on the dye in solution, on solid state samples and for the latter in contact to a I−/I3− redox electrolyte typical for dye-sensitized solar cells to elucidate the effect of each component in the observed dynamics. D149 in a solution of 1:1 acetonitrile and tert-butyl alcohol shows excited-state lifetimes of 300±50 ps. This signature is severely quenched when D149 is adsorbed to ZnO, with the fastest component of the decay trace measured at 150±20 fs due to the charge-transfer mechanism. Absorption bands of the oxidized dye molecule were investigated to determine regeneration times which are in excess of 1 ns. The addition of the redox electrolyte to the system results in faster regeneration times, of the order of 1 ns.
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- Date Issued: 2013
X-ray photoelectron spectroscopy analysis of the effect of alkyl-and arylthio substituents on manganese phthalocyanines for self-assembled monolayer formation on gold
- Authors: Coates, Megan , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190490 , vital:44999 , xlink:href="https://doi.org/10.1016/j.elecom.2013.03.019"
- Description: Self-assembled monolayers of an octa-substituted alkylthio and arylthio manganese phthalocyanines were formed on gold. X-ray photoelectron spectroscopy was used to analyse both of the phthalocyanine layers on gold. Approximately 60% of the sulphur groups in the aryl substituted-SAM surface were bound to gold through the cleavage of the C S bond, as opposed to only 37% for the alkyl substituted-SAM.
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- Date Issued: 2013
Zinc (II) 2, 9, 16, 23-tetrakis [4-(N-methylpyridyloxy)]-phthalocyanine anchored on an electrospun polysulfone polymer fiber: Application for photosensitized conversion of methyl orange
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232741 , vital:50020 , xlink:href="https://doi.org/10.1016/j.molcata.2012.10.001"
- Description: In this work, a comparative study of photodegradation of methyl orange, an azo dye, in homogeneous aqueous solution of a quarternized cationic zinc phthalocyanine and a heterogeneous catalytic system based on the same phthalocyanine anchored on polysulfone polymer fiber is presented. In both cases, conversion involved the azo bond of the dye with no detectable opening up of the aromatic benzene rings. The reaction kinetics in both cases were consistent with first order with the conversion occurring in the homogeneous system being faster than when the functionalized polymer fiber was used. The reaction products consisted of a coupling product as well as a series of oligopolymeric products.
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- Date Issued: 2013