A series of alkynylplatinum(II) polypyridine complexes with
4,4′,4′′-tricarboxy-2,2′:6′,2′′-terpyridine and 4,4′-dicarboxy-2,2′-bipyridine as TiO2
anchoring functionalities, has been successfully synthesized. Their photophysical,
electrochemical and luminescence properties have been extensively studied. The
excited state properties were probed using nanosecond transient absorption
spectroscopy. [Pt(tctpy)(C≡C-Th-BTD-Th)][NnBu4]2 displayed a long-lived transient
signal which was tentatively assigned to result from the formation of a
charge-separated state, which could be alternatively described as a
[Pt(tctpy)???(C≡C-Th-BTD-Th)+?] state, with the charge recombination rate constant
determined to be 2.9 × 105 s?1. The excited state redox potentials for the oxidation
process were determined and the data confirmed the ability of the complexes to inject
an electron into the conduction band of TiO2. The majority of the complexes were
found to sensitize the nanocrystalline TiO2 and exhibit photovoltaic properties, which
have been characterized by current-voltage measurements under illumination of air
mass (AM) 1.5G sunlight (100 mW cm–2).
A new class of molecular dyads comprising metalloporphyrin-linked
alkynylplatinum(II) polypyridine complexes was synthesized and characterized. Their
photophysical, electrochemical and luminescence properties have been studied in
detail. The excited state properties were probed using nanosecond transient absorption
spectroscopy which indicated the formation of a charge-separated state involving the
porphyrin radical anion, [Por??－(C≡C)Pt+?]. The excited state redox potentials for the
oxidation process were also determined with the data supporting the capability of the
complexes to inject an electron into the conduction band of TiO2. The majority of the
complexes were found to sensitize the nanocrystalline TiO2 and exhibit photovoltaic
properties, as characterized by current-voltage measurements under illumination of air
mass (AM) 1.5G sunlight (100 mW cm–2).
A series of organic materials consisting of a triphenylamine-based donor with
oligothiophene or oligothienylenevinylene based-conjugated linker and dicyanovinyl,
tricyanovinyl or cyanacrylic acid groups as acceptor, was synthesized and
characterized. Their photophysical, electrochemical, thermal and luminescence
properties were studied. Transient absorption spectra of TPA-OTV-DCN in
dichloromethane solution on the pico- to nanosecond timescale were recorded after
femtosecond laser excitation at 400 nm. A transient signal at ca. 700 nm was
tentatively assigned to result from the formation of a charge-separated
[(TPA-OTV)+??DCN??] state with the charge recombination rate constant determined
to be 5.3 × 109 s?1. The energy levels of the LUMOs of TPA-OTV1-DCN,
TPA-OTV2-DCN, TPA-OTV3-DCN TPA-TAZ1-DCN, TPA-TAZ2-DCN and
TPA-o-4Th-DCN were calculated to be of ca. ?3.9 eV, establishing the formation of a
downhill driving force for the energetically favorable electron transfer process
involving the injection of an electron into the LUMO of the C60 acceptor. The
majority of the compounds were found to exhibit photovoltaic properties. The
photovoltaic responses were characterized by current-voltage measurements under
illumination of air mass (AM) 1.5G sunlight (100 mW cm–2). / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/208172 |
| Date | January 2012 |
| Creators | Kwok, Chi-ho, 郭志豪 |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Rights | Creative Commons: Attribution 3.0 Hong Kong License, The author retains all proprietary rights, (such as patent rights) and the right to use in future works. |
| Relation | HKU Theses Online (HKUTO) |
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