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Double-Layered NiO Photocathodes for p-Type DSSCs with Record IPCE
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
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2010 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 22, no 15, 1759-1762 p.Article in journal (Refereed) Published
Abstract [en]

A way to achieve a high-efficiency dye-sensitized solar cell is to combine an n-type TiO2-based photoanode with a p-type photocathode in a tandem configuration. The development of an efficient photocathode is, at present, the key target. We have optimized the NiO, I-3(-)/I- p-DSSC system to obtain record photocurrent, giving 64% incident photon-to-current conversion efficiency (IPCE) and 5.48 mAcm(-2) J(SC).

Place, publisher, year, edition, pages
2010. Vol. 22, no 15, 1759-1762 p.
National Category
Organic Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-24441DOI: 10.1002/adma.200903151ISI: 000277369600011Scopus ID: 2-s2.0-77951192634OAI: oai:DiVA.org:kth-24441DiVA: diva2:349938
Note
QC 20100909Available from: 2010-09-09 Created: 2010-09-09 Last updated: 2017-12-12Bibliographically approved
In thesis
1. The study of organic dyes for p-type dye-sensitized solar cells
Open this publication in new window or tab >>The study of organic dyes for p-type dye-sensitized solar cells
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis concerns the study of D–π–A type dyes as sensitizers for NiO-based p-type dye-sensitized solar cells. The focus has been on the design and synthesis of efficient dyes and the identification of parameters limiting the solar cell performance.

We have developed a new design strategy for the dyes: upon photoexcitation of the dye, the electron density is moving from the part that is attached to the semiconductor towards the part which is pointing away. This intramolecular charge transfer provides an efficient pathway for the following charge transfer processes. The first organic dye, composed of a triphenylamine (TPA) moiety as the electron-donor, dicyanovinyl groups as the electron-acceptors and linked by thiophene units, showed much better photovoltaic performance than other dyes reported at the same time, turning it into a model for future dye design.

A series of dyes with different energy levels were synthesized and characterized on NiO-based devices using iodide/triiodide as redox couple. Lower photovoltaic performance was obtained for the dye with less negative reduction potential due to the insufficient driving force for dye regeneration. We have investigated the symmetric and unsymmetric structures of the dyes. The breaking of molecular symmetry did not significantly broaden the absorption spectrum, or improve the efficiency. In addition, we have tuned the molecular structure to prevent charge recombination. Increasing the distance between the anchoring group and the electron-acceptor was an effective way to improve the device efficiency. Besides TPA-based compounds, a zinc porphyrin dye was also synthesized and tested in p-type solar cells. However, the solar cell performed less well due to its narrow absorption band and the tendency for aggregation. Co-sensitization of the TPA-based dye with the porphyrin dye did not result in higher photovoltaic performance.

After optimization of the dye structure, the highest overall conversion efficiency was achieved for the P5-sensitized solar cell, based on 1.5 μm NiO film prepared from NiCl2 and the F108 template precursor, and an acetonitrile-based electrolyte.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. 72 p.
Series
Trita-CHE-Report, ISSN 1654-1081
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-24406 (URN)978-91-7415-695-9 (ISBN)
Public defence
2010-09-23, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100909Available from: 2010-09-09 Created: 2010-09-07 Last updated: 2010-09-09Bibliographically approved
2. Functional Photo-electrochemical Devices for Solar Cellsand Solar Fuels Based on Molecular Components
Open this publication in new window or tab >>Functional Photo-electrochemical Devices for Solar Cellsand Solar Fuels Based on Molecular Components
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis concerns the development and the study of molecular functional photo-electrochemical cells (PEC) for solar cells and solar fuels.

The first chapter gives a general introduction about photosynthesis, dye-sensitized solar cell and photo-electrochemical device for water splitting.

The second chapter describes a TiO2-Co-catalyst electrode manufactured by a direct photo-deposition method. The electrode showed activity for electrochemical water oxidation in an electrochemical device.

In the third chapter, a photo-electrochemical cell (PEC) with two-electrodes for visible light driven water splitting has been successfully demonstrated. One electrode was a photo-anode, which assembled a ruthenium water oxidation catalyst (complex 1) into a dye-sensitized porous nanostructured TiO2 electrode by employing a cation-exchange membrane (Nafion). The other electrode was platinum which was used as a passive cathode for proton reduction.

In the fourth chapter, an earth abundant metal complex with an anchoring group (cobalt complex 2) was synthesized and investigated as water oxidation catalyst. This complex was further applied into a photo-anode in a PEC. The photo-anode was assembled by co-sensitization of complex 2 to a dye-sensitized porous nanostructured TiO2 electrode. The PEC device gave ca. 250 υA/cm2 photo-current and 7.2 % IPCE without applying any bias voltage, which is much higher than the reported results in the sample type of PEC. Meanwhile, we have shown that the catalytic effect is not from free cobalt ions, CoOx film or nanoparticles formed in situ by using complex 2 in the device.

The last two chapters describe an optimization of the NiO films prepared in two steps rather than one step film and applied in p-type DSSCs. This optimized film could adsorb more dye (P1), leading to a significant light harvesting efficiency (LHE) and IPCE in DSSCs. We further combined this P1 sensitized photo-cathode with a hydrogen evolution catalyst (complex 3) and applied this photo-cathode into a PEC for visible light hydrogen evolution.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. 71 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2012:51
Keyword
artificial photosynthesis, dye sensitized solar cell, hydrogen generation catalyst, nickel oxide (NiO), titanium dioxide (TiO2), water oxidation catalyst, water splitting
National Category
Other Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-103623 (URN)
Public defence
2012-11-09, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20121017

Available from: 2012-10-17 Created: 2012-10-16 Last updated: 2012-10-17Bibliographically approved

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