Yet another innovation in solar is gaining ground in notoriety and funding — organic photovoltaics. And what does this new breakthrough have to offer? Another possible solution to the high manufacturing cost of solar PV cells. In addition to that, organic solar cells would be light and flexible, two big advantages in the world of building integrated systems. However, organic cells, made from carbon-based molecules, are also prone to two big drawbacks all too common in solar photovoltaic research: inefficiency and short lifetime.

While organic molecules are already manufactured in extremely large doses and, subsequently, sold cheap, and organic solar cells are much easier to make than silicon-based cells, their efficiency halts at around 5% and they tend to degrade in the light.

But first, to the advantages. Organic solar cells are constructed using molecules, whereas silicon cells are built using atoms. The difference may seem tiny, and it is, but even a tiny difference at the molecular level can have far reaching implications. Quite simply, molecules are larger than atoms and therefore easier to work with. They can even be dissolved in a solvent, turned into ink, and printed like a newspaper. And as you can see by the price of your morning newspaper, printing is cheap and fast.

It is also easier to make new designs using molecules. It is rather difficult to form new materials when working with atoms, but the possibilities become immense when the focus is changed to molecules. There is virtually no limit to the number of molecules that could be used to create an organic photovoltaic cell. Essentially, this means that organic solar cells could be made custom for a particular market or application. For example solar cells can be made that are camouflaged or to match whatever roof color.

Another benefit of the many molecular choices available to scientists and manufacturers is having the pick of the litter. Because developers can select only the most efficient, light-absorbing molecules, solar cells can be made 1,000 times thinner than silicon cells, which offers oodles of savings in production costs. This also renders the cells flexible, easy to print and transport, and easy to install as they could be simply unrolled onto a customer’s roof.

These benefits are certainly of great importance and very exciting to solar technology researchers and companies. Nonetheless, their shortcomings are equally as substantial. Unfortunately, electrical charges move rather slowly through the organic cell’s molecular makeup. In order to extract electricity efficiently, charges need to move as fast as they can through the carefully placed atoms in a silicon solar cell. Because molecules are much less ordered than silicon crystals, charges tend to get trapped or disappear and the flow of electrons is disrupted and, consequently, efficiency is severely limited.

Lifetime is another major issue for organic photovoltaics. Materials made from molecules are inherently more volatile than tediously constructed, atom-based cells. Molecules tend to interact easily with other molecules such as water and oxygen and therefore change. By way of this unwanted metamorphosis, the molecules change and may absorb less light or produce fewer charges. In the end, organic cells are more likely to degrade while exposed to sunlight — not a prime characteristic when attempting to harness solar energy.

Nonetheless, the notable benefits of organic solar cells are reason enough to pursue a finished product, despite the lofty obstacles that stand in the way. And excitement is growing worldwide with $570 million dollars recently set aside for organic photovoltaic research. A commercially viable solution is still miles away but it has become apparent that major players in the solar industry are willing to back organic solar and therefore it is likely to make a dent, at least in small, niche markets.

Link: RenewableEnergyWorld