Dye-sensitized, silicon-free solar cells have passed an important viability test at a Chinese lab. Do innovations like this herald the age of cheap solar power?

The sensitized films, which are far less expensive than traditional photovoltaic panels, were previously known for their inefficiency, a plague on the entire solar industry (which only converts 15-30% on average) but thin-film solar in particular (the new record for this cell was 8.2%).  Thin-film has achieved far higher conversion rates in the past, but the Chinese test is significant because the sensitized film it was using had no chemical solvents involved in the production–that is, in addition to being a renewable energy source, it was also eco-friendly, and will be easy to manufacture on an industrial scale.

There are different types of solar cells?

While traditionally solar is thought of one of two ways–passive solar, and photovoltaics, the development of dye-sensitized film has led to the emergence of a new solar technology.  While passive solar is relatively cheap and simple, it doesn’t actually generate electricity.  Passive solar is great for heating your home, or water, but only one of the forms of active solar can run all the cool gadgets that you own.  This technology is called “photvoltaic” for reasons imminently clear to anybody that’s taken a classical language.  The sun shines down onto a solar cell, which is packed with silicon modules, which form an electrical field when their electrons get excited by the sun’s rays.*  The problem with photovoltaics is that they’re expensive to produce –silicon is a semiconductor, and the same properties that make it such a good solar material have caused it to be in high demand for the electronics industry, as well.  Good luck finding anything that you use daily that requires power that doesn’t have silicon it it, now that processors are everywhere.

Thin film, therefore, works towards the same end, but travels a totally different route:  it separates the tasks that the silicone inherently takes on by using a series of materials that, as it turns out, are smaller, cheaper, and far more easy to obtain.  Titanium dioxide, for example, is frequently used in paint bases.  The technology also has a dramatically lower manufacturing cost–thin film in production looks like newspaper being printed, at 1,000 feet per minute.

Why the Chinese lab test matters

Sensitized dye has always struggled with efficiency, like we mentioned above–even the versions made with the toxic solvents could only pull down about 11%.  The easy way to compensate for this shortcoming is with volume, right?  It’s clean, renewable energy.

Well, as it turns out, using volume to compensate leaves you limited to large-scale commercial applications for solar, a market that the thin film people want to be sure, but don’t want to limit themselves to.  There’s also the issue of the thin film containing toxic solvents, which are carefully sealed inside.  More volume means more chances for something bad to happen, unfortunately.  Or it did–now that there’s a safe solution to the composition issue, and it’s becoming more and more competitive, there’s clean, SAFE, cheap solar tech on the horizon.

*Painfully oversimplified.

More Reading:

New Efficiency Benchmark For Dye-Sensitized Solar Cells (EurekAlert)
Dye-Sensitized Solar Cells (Wikipedia)
Photvoltaic Cells (HowStuffWorks)

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