New dye solar cell structures deliver sought-after stability

27 Sep 2010

Breakthrough research at the Weizmann Institute of Science in Israel has attracted the attention of dye solar cell firm 3G Solar.

The researchers at the Weizmann Institute have developed structures for dye-sensitised solar cells (DSSCs) that separate the process of absorbing light from that of carrying electrical charge, making for more stable devices.

3G Solar, which received further venture capital funding in August as part of a new commercial strategy, is spending some of its new funds on R&D into the technology.

Barry Breen, CEO of 3G Solar, comments: '3G Solar is raising the bar for higher efficiency, lower cost and greater durability of printed solar cells, using DSSC and QD technology. Our advances will achieve access to a broad range of solar electricity markets.'

Förster resonance energy transfer

The process developed at the Weizmann Institute is called Förster resonance energy transfer (FRET). Researchers Dan Oron and Arie Zaban used colloidal semiconductor quantum dots (QDs) that channel absorbed light to the charge separating dye molecules. By separating the two processed, the QDs are not an active part of the charge carrying process and therefore do not dissipate light energy as heat. The result is a DSSC structure that can offer better efficiencies and greater stability.

Oron comments: 'Dye cells typically perform quite well, but there are a few inherent properties that create significant limitations - most notably that the only really active area on the cell is between the electrode and the electrolyte.

'FRET introduces the optical activity into the bulk volume of the dye cell, rather than staying in this well-defined area.'

The result is DSSCs that are more stable, and offer good efficiencies in thinner cell structures.

Organic dyes

The researchers and 3G Solar are now working on organic dyes that are suited to the conversion of energy harvested by the QDs.

'The missing link now is in the synthesis of the appropriate organic dyes. We do not need the standard dyes, like ruthenium, as they have broadband absorption.'

While the creation of narrow band dyes is limited - as most DSSC developments are looking for broadband absorption - Oron is confident that suitable materials will be straightforward to develop.

'There are lots of research groups in the world making near-infrared dyes - they just need to bind well and have proper band alignment. I guess that results can be obtained with just a small change in existing materials,' he adds.

+Plastic Electronics Volume 3, issue 2, will include a series of special features on the commercialisation of dye-sensitised solar cells. The magazine will also be appearing at the forthcoming 4th International Conference on the Industrialisation of Dye Solar Cells, 1-4 November 2010.
To subscribe in time for the next issue, visit our subscriptions page. For more information, email Editor Dan Rogers at daniel.rogers@pira-international.com.