Characterization of the optical properties of metalloporphyrins in TiO2 sol-gel films for photon upconversion applications
Date
2013-05-30
Authors
Journal Title
Journal ISSN
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ORCID
Type
Degree Level
Masters
Abstract
The photophysical properties of a series of Zn (II) porphyrins adsorbed onto a
semiconductor were investigated using steady-state absorbance and emission
measurements. The ability of the porphyrins to undergo triplet-triplet annihilation (TTA), a photophysical process through which photons in the red and near-infrared (NIR) regions of the optical spectrum can be converted into higher energy photons (upconversion), was explored. Aggregation capabilities were determined to verify possibility of these molecules to undergo triplet-triplet annihilation (TTA). TTA has significant potential for increasing the efficiency of dye-sensitized solar cells (DSSCs) by
upconverting photons in the energy rich NIR region of the solar spectrum. A key
requirement for efficient TTA is aggregation of the sensitizer dye, and in this thesis, we have examined the aggregation of porphyrins in TiO2-based sol-gel films. Solution phase absorption and emission studies were conducted using zinc (II) tetraphenylporphyrin and
three of its functionalized derivatives, tetra(4-aminophenyl)porphyrin Zn(II), tetra(4-carboxyphenyl)porphyrin Zn(II), and tetra(4-sulfonatophenyl)porphyrin Zn(II), to
evaluate their potential as DSSC sensitizers on TiO2 thin films. Mesoporous TiO2 thin films were synthesized, using a polymer-templating sol-gel route, and characterized with
tunneling electron microscopy (TEM), atomic force microscopy (AFM), and UV-Vis absorbance measurements. Spectroscopy measurements were also carried out on porphyrin-sensitized TiO2 thin films and compared to solution-based results. A simple DSSC was constructed and used to further explore the application of zinc (II) porphyrin sensitizers in photovoltaic applications.
Description
Keywords
photon upconversion, triplet-triplet annihilation, TTA, porphyrins, dye-sensitized solar cells, DSSCs
Citation
Degree
Master of Science (M.Sc.)
Department
Chemistry
Program
Chemistry