Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Capturing Sunlight

Indoline dyes improve efficiency of solar cells

Solar cell technology is marching ahead, though it still struggles with the two problems: efficiency and high production costs. In collaboration with Satoshi Uchida at the University of Tokyo, Michael Grätzel and his research group at the Swiss Federal Institute of Technology in Lausanne have now developed new sensitizers that should help an inexpensive type of solar cell to be more efficient. As they report in the journal Angewandte Chemie, the sensitizers are based on the dye indoline.

Some years ago, Grätzel developed photoelectrochemical solar cells that are inexpensive, easy to produce, and able to withstand long exposure to light and heat. These "Grätzel cells" contain a mesoscopic layer of titanium oxide (TiO2) particles coated with a sensitizing dye. Upon irradiation with light, electrons are injected from the dye adsorbed on the TiO2, which are then transferred to the conducting band of the TiO2 and collected at the back contact, and carried away by an external circuit. In order for the cell to work, the electrons that are injected into the TiO2 must not recombine with the oxidized dye.

To prevent this, the cell contains an electrolyte solution with negatively charged iodide and triiodide ions as a redox couple dissolved in a solvent, which immediately reduce the holes created in the dye. The main disadvantage of using volatile organic solvent in the electrolyte is the need for encapsulation of the electrolyte. Ionic liquids are an alternative to the use of these volatile solvent. These salts exist as liquids at low temperatures and do not evaporate. However, the high viscosity of these electrolytes is detrimental to the mass transport and consequently a problem for obtaining high efficiency.

... more about:
»Efficiency »Electron »Grätzel »TiO2 »dye »electrolyte »sensitizer

Grätzel and his team compensated for this loss of efficiency by optimizing the sensitizer. In place of the usual ruthenium dyes, they used tailor-made organic dyes based on indoline, which have a higher molar extinction coefficient. This allows the TiO2 films to be thinner, in turn reducing the electron path length. The combination thus attained an energy conversion yield of 7.2 %. This is a record for this type of cell (organic dye, ionic liquid, titanium oxide).

In this case the efficiency of the dye as a sensitizer is not only dependent on its chromophore, but also on its interfacial properties. So using a dye with an additional hydrocarbon chain has improved the performance by retarding the back electron reaction.

Author: Michael Grätzel, Ecole Polytechnique Fédérale de Lausanne (Switzerland),

Title: Organic Dye-Sensitized Ionic Liquid Based Solar Cells: Remarkable Enhancement in Performance through Molecular Design of Indoline Sensitizers

Angewandte Chemie International Edition 2008, 47, No. 10, 1923–1927, doi: 10.1002/anie.200705225

Michael Grätzel | Angewandte Chemie
Further information:

Further reports about: Efficiency Electron Grätzel TiO2 dye electrolyte sensitizer

More articles from Life Sciences:

nachricht Signaling Pathways to the Nucleus
19.03.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht In monogamous species, a compatible partner is more important than an ornamented one
19.03.2018 | Max-Planck-Institut für Ornithologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

A new kind of quantum bits in two dimensions

19.03.2018 | Physics and Astronomy

Scientists have a new way to gauge the growth of nanowires

19.03.2018 | Materials Sciences

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Science & Research
Overview of more VideoLinks >>>