Advanced

Femtosecond Spectroscopic Investigations of the Functionalization of Iron Carbene Photosensitizers

Mateos, Helena LU (2014) KEMP39 20141
Department of Chemistry
Abstract
Dye sensitized solar cells (DSSCs) recently attracted much attention as a relatively efficient and inexpensive light-to-electricity energy conversion solution. So far the best performing DSSC devices were produced employing ruthenium (RuII) complexes as the active material, nevertheless limited resources of this metal initiated the research of new alternatives. Iron is one of the most abundant elements on earth and has similar electronic properties to ruthenium, being in the same group 8 in the periodic table, therefore, most recent studies of DSSCs are based on iron complexes. In this thesis, the process of electron injection from a novel iron (FeII) complex based on σ-donating N- heterocyclic carbene (NHC) ligands into the conduction... (More)
Dye sensitized solar cells (DSSCs) recently attracted much attention as a relatively efficient and inexpensive light-to-electricity energy conversion solution. So far the best performing DSSC devices were produced employing ruthenium (RuII) complexes as the active material, nevertheless limited resources of this metal initiated the research of new alternatives. Iron is one of the most abundant elements on earth and has similar electronic properties to ruthenium, being in the same group 8 in the periodic table, therefore, most recent studies of DSSCs are based on iron complexes. In this thesis, the process of electron injection from a novel iron (FeII) complex based on σ-donating N- heterocyclic carbene (NHC) ligands into the conduction band of titanium dioxide (TiO2) is investigated as a function of different conditions. Processes like the effect of molecular structure and presence of the electrolyte are also analyzed. The time-resolved absorption (TA) spectroscopy studies allowed to investigate ultrafast processes occurring within timescales as short as femtoseconds. The introduction of the carboxylic acid group into the molecular complex resulted in double the lifetime of metal-to-ligand charge transfer (MLCT) triplet state, which is an indication of more efficient electron generation processes. It was also found that the presence of the electrolyte alone could increase the lifetime of MLCT3 states. Finally, observations of transient absorption in films of TiO2 with the active material suggested possible electron injection, which is essential step for current generation in solar cell devices. (Less)
Popular Abstract
The actual cost of production of conventional solar cells is too high, and they are only profitable for large commercial applications, therefore, research of new alternatives of solar cells is becoming increasingly important. Among this kind of research-cells, dye-sensitized solar cells are a promising future alternative due to the possible low cost and high performance ratio that could achieve, having the possibility of becoming good enough to be competitive with fossil fuel electrical power generation. Nevertheless, one of the main problems of this cells is the expensive materials needed for their fabrication based on ruthenium. The use of much cheaper iron materials instead, could be a future possibility and for this reason, further... (More)
The actual cost of production of conventional solar cells is too high, and they are only profitable for large commercial applications, therefore, research of new alternatives of solar cells is becoming increasingly important. Among this kind of research-cells, dye-sensitized solar cells are a promising future alternative due to the possible low cost and high performance ratio that could achieve, having the possibility of becoming good enough to be competitive with fossil fuel electrical power generation. Nevertheless, one of the main problems of this cells is the expensive materials needed for their fabrication based on ruthenium. The use of much cheaper iron materials instead, could be a future possibility and for this reason, further investigations of these molecules are of crucial importance. In this thesis, a promising new material based on iron is investigated by simulation of different performing solar-cell conditions.
Dye sensitized solar cells are a new promising technology for harvesting solar energy. It’s advantages compared to conventional solar cells is that they are simple to produce, easy to incorporate into materials, and that they show high performance ratios, enabling them to be competitive with fossil fuel electrical power generation. One of the main challenges of these cells is that the most efficient ones are achieved using the rare earth element Ruthenium, of which the abundance is too low for large scale production. Iron is an obvious replacement candidate for Ruthenium, but so far no one has been able to produce an efficient iron compound for this purpose. In this thesis, a promising new material based on iron is investigated by simulation of different performing solar-cell conditions, and it is shown for the first time how the iron compound converts the solar energy into electricity. (Less)
Please use this url to cite or link to this publication:
author
Mateos, Helena LU
supervisor
organization
course
KEMP39 20141
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Dye sensitized solar cells, DSSC, transient absorption, metal-ligand charge transfer, electron injection, iron complexes, kemisk fysik, chemical physics
language
English
id
4780449
date added to LUP
2014-11-18 15:39:53
date last changed
2014-11-18 15:39:53
@misc{4780449,
  abstract     = {Dye sensitized solar cells (DSSCs) recently attracted much attention as a relatively efficient and inexpensive light-to-electricity energy conversion solution. So far the best performing DSSC devices were produced employing ruthenium (RuII) complexes as the active material, nevertheless limited resources of this metal initiated the research of new alternatives. Iron is one of the most abundant elements on earth and has similar electronic properties to ruthenium, being in the same group 8 in the periodic table, therefore, most recent studies of DSSCs are based on iron complexes. In this thesis, the process of electron injection from a novel iron (FeII) complex based on σ-donating N- heterocyclic carbene (NHC) ligands into the conduction band of titanium dioxide (TiO2) is investigated as a function of different conditions. Processes like the effect of molecular structure and presence of the electrolyte are also analyzed. The time-resolved absorption (TA) spectroscopy studies allowed to investigate ultrafast processes occurring within timescales as short as femtoseconds. The introduction of the carboxylic acid group into the molecular complex resulted in double the lifetime of metal-to-ligand charge transfer (MLCT) triplet state, which is an indication of more efficient electron generation processes. It was also found that the presence of the electrolyte alone could increase the lifetime of MLCT3 states. Finally, observations of transient absorption in films of TiO2 with the active material suggested possible electron injection, which is essential step for current generation in solar cell devices.},
  author       = {Mateos, Helena},
  keyword      = {Dye sensitized solar cells,DSSC,transient absorption,metal-ligand charge transfer,electron injection,iron complexes,kemisk fysik,chemical physics},
  language     = {eng},
  note         = {Student Paper},
  title        = {Femtosecond Spectroscopic Investigations of the Functionalization of Iron Carbene Photosensitizers},
  year         = {2014},
}