Michael Gratzel awarded 2010 millennium technology prize

The 2010 Millennium Prize Laureate Michael Grätzel is the father of third generation dye-sensitized solar cells. Grätzel cells, which promise electricity-generating windows and low-cost solar panels, have just made their debut in consumer products.

Professor Michael Gratzel of the Lausanne Federal Technology Institute received the €800,000 (£660,000) prize at a ceremony in Helsinki.

Dye-sensitised cells (DSCS) have emerged alongside organic solar photovoltaics (PV) as a technology that might just transform solar energy prospects by delivering cheap "commodity" PV.

This technology was launched publicly in 1991. Early cells were 7%–8% efficient, though researchers have since boosted this figure to around 11%. As with organic PV, mainly low-cost materials are used. However, the energy conversion mechanism is different from organic PV.

A dye-sensitised solar cell can be likened to a conventional battery in which an external stimulus is needed — in this case, light. Light is used to initiate the electrochemical reaction that produces electron flow and hence current. Thus the overall action is photo-electrochemical. Such a cell requires a fourth ingredient over and above the well-known anode-cathode-electrolyte trio: a material that can release electrons when excited by photons of light. Some light-sensitive dyes have this power, as different dyes and colours are sensitive to different light wavelengths.

Semiconductor action is also involved, provided by a layer of nanostructured titanium dioxide, to which the dye is attached. The associated band gap dynamics mean that the various material layers can be extremely thin, in contrast to the “thick” crystalline silicon currently used in conventional solar cells.

Innovative applications will help drive demand for dye-sensitised solar cell technology. Watchmaker Swatch plans to launch a dye-sensitised solar cell powered watch using cells laid directly onto metal substrates. Konarka has worked with Textronics on weaving dye-sensitised solar cell fibres into fabrics usable in handbags, clothing, curtains, blinds, tents, vehicle covers, etc.

And in a recent report, analyst NanoMarkets LLC cites good performance in dim or variable light as probably the leading dye-sensitised solar cell advantage at present. This explains why solar chargers are likely to be the first products to market. NanoMarkets suggests that the flexibility and cost advantages will become predominant later in the technology's evolution, to be realised in products ranging from smart curtains and wearable fabrics, to tiles for roofs or walls.

Costs per watt generated could, if early promise is borne out, eventually fall well below those for conventional power generation, a breakthrough that still seems well in the future for silicon-based PV. Proponents even suggest that dye-enabled solar PV could become ubiquitous, attain commodity status and prove transformational for renewable energy prospects.

Read more on Dye-sensitised cells (DSCS).

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Policy, investment and markets  •  Solar electricity