Marek, Peter L. (2012)
Biomimetic Dye Aggregate Solar Cells.
Technische Universität Darmstadt
Ph.D. Thesis, Primary publication
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Dissertation Peter Marek 2012 -
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Item Type: | Ph.D. Thesis | ||||
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Type of entry: | Primary publication | ||||
Title: | Biomimetic Dye Aggregate Solar Cells | ||||
Language: | English | ||||
Referees: | Hahn, Prof. Dr.- Horst ; Balaban, Prof. Dr. T. Silviu ; Jaegermann, Prof. Dr. Wolfram | ||||
Date: | 2 July 2012 | ||||
Place of Publication: | Darmstadt | ||||
Date of oral examination: | 20 April 2012 | ||||
Abstract: | A biomimetic self-assembling dye, which forms aggregates that mimic the natural light-harvesting system of special photosynthetic active bacteria, has been investigated towards its applicability to solar cells. This fully synthetic dye, self-assembles to orderly structured nano- to micrometer sized rod-shaped aggregates, which might improve solar cells based on conventional organic dyes. In order to use the full potential of the dye aggregates, the self-assembly needed to be controlled and a suitable solar cell concept for their implementation developed. In the first part of this thesis it has been investigated how the self-assembly can be controlled in order to achieve dye aggregates with a high internal order and size-confinement at least in one dimension. This dimension should not exceed the exciton diffusion length, what is the maximum path length, an excited state, which originates by the absorption of light, can travel within an aggregate. In the second part of this thesis the findings from the first part have been applied to construct and test first solar cell prototypes with such controlled dye aggregates. In contrast to the chlorophylls of plants, the self-assembling bacteriochlorophylls of green sulfur bacteria, which served as model for our dye, do not require proteins for the assembly of functional light-harvesting systems. This allows to mimic the light-harvesting system fully synthetically in large scale in order to realize low-cost, light-weight and environmentally friendly solar cells. As nature gives the proof of principle in practice for the functionality of such dye aggregates, this work has been carried out in order to investigate the transferability of this concept to technology. Various methods have been investigated in order to decrease the size of the aggregates while maintaining as far as possible their highly ordered internal structure. These included the steric hindering of the self-assembly within voids of different porous TiO2 layers and on zinc oxide nanorod substrates, the kinetic growth-hindering at low temperatures and a size-selective deposition by dielectrophoretic forces. Other investigated techniques to deposit the aggregates were spin-coating, spraying, precipitation and a two-step process, where at first an amorphous layer was deposited suppressing the self-assembly in order to initiate afterwards a reorganization to the desired aggregates. The degree of success was monitored mainly by absorption spectroscopy in combination with scanning electron microscopy (SEM). Whereas the absorption spectroscopy gave a value of the average degree of the aggregates' internal order, the SEM allowed an assessment of the aggregates' dispersity, i.e. the fraction and distribution of different morphologies, sizes and their alignment on the substrate. Finally, these aggregates have been implemented into solar cells, designed to combine the advantages of hybrid solar cells and solid-state dye-sensitized solar cells (ss-DSSCs). We call them: dye aggregate solar cells (DASCs). They were constructed on flat and different porous TiO2 structures, which were sensitized by the dye aggregates for visible light with supplement for the hole transport by the transparent organic hole transport material spiro-MeOTAD. The performance of the DASCs was compared with that of ss-DSSCs based on the common ruthenium dye N719, which is often used as reference. Additional investigations have been done using the atomic layer deposition (ALD) technique to apply dense hole-blocking TiO2 layers onto the transparent conductive substrates with a fluorine doped tin oxide (FTO) layer. As application method for the gold counter electrode the sputtering technique was employed for these solar cells as alternative to the conventional evaporation technique. The development of a special contacting device allowed miniaturized solar cells to be contacted without the need for pre-structuring the commercial FTO-layers. |
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Uncontrolled Keywords: | PhD Thesis, Bionics, solid-state, dye, aggregate, sensitized, solar cells, DASC, DSSC, DSC, SDSC, ss-DSSC, organic, hybrid, Bacteriochlorophyll, BChl, Bacteria, self-assembly, light harvesting system, antenna system, LHS, mesoporous, coarse porous, TiO2, Titania, Schottky barrier, FTO, TCO, ALD, SEM, morphology, airbrush, sprayed solar cells, efficient, low light, low cost, environmentally friendly | ||||
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URN: | urn:nbn:de:tuda-tuprints-30177 | ||||
Additional Information: | In this PhD thesis a new type of solar cell has been developed with high potential for low cost and weak light applications. |
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Classification DDC: | 500 Science and mathematics > 500 Science 600 Technology, medicine, applied sciences > 620 Engineering and machine engineering |
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Divisions: | 11 Department of Materials and Earth Sciences | ||||
Date Deposited: | 12 Jul 2012 08:48 | ||||
Last Modified: | 09 Jul 2020 00:10 | ||||
URI: | https://tuprints.ulb.tu-darmstadt.de/id/eprint/3017 | ||||
PPN: | 386255962 | ||||
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