The solar cells you see on many roofs today are built out of silicon, the same stuff that powers your computer and smartphone. The reasons for this are many but it mostly comes down to silicon’s durability, semiconductor properties and ease at which we can mass produce them thanks to our investments in semiconductor manufacturing. However they’re not the only type of solar cell we can create, indeed there’s a different type that’s based on polymers (essentially plastic) that has the potential to be much cheaper to manufacture. However the technology is still very much in its infancy with the peak efficiency (the rate at which it can convert sunlight into electricity) being around 10%, far below even that available from commercial grade panels. New research however could change that dramatically.
The current standard for organic polymer based solar cells utilizes two primary materials. The first is, predictably, an organic polymer that can accept photons and turn them into electronics. These polymers are then doped with a special structure of carbon called fullerene, more commonly known as buckyballs (which derive their name from their soccer ball like structure). However the structures that form with current manufacturing processes are somewhat random. This often means that when a photon produces a free electron it recombines before it can be used to generate electricity which is what leads to polymer cell’s woeful efficiency. New research however points to a way to give order to this chaos and, in the process, greatly improve the efficiency.
Researchers at the USA’s Department of Energy’s SLAC National Accelerator Laboratory have developed a method to precisely control the layout of the polymers and fullerene, rather than the jumbled mess that is currently standard. They then used this method to test various different arrangements to see which one produced the highest efficiency. Interestingly the best arrangement was one that mimicked the structure we see in plants when they photosynthesize. This meant that the charge created in the polymer by a photon wasn’t recombined instantly like it usually was and indeed the polymers were able to hold charge for weeks, providing a major step up in efficiency.
Whilst this research will go a long way to solving one of the major problems with polymer based solar cells there are still other issues that will need to be addressed before they become commercially viable. Whilst a typical silicon solar cell will last 20 years or more a polymer one will only last a fraction of that time, usually only 4 years or so with current technology. For most solar cells that amount of time is when they’ve just paid back their initial investments (both in terms of energy and revenue) so until they get past this roadblock they will remain an inferior product.
Still research like this shows there’s potential for other technologies to compete in the same space as silicon, even if there are still drawbacks to be overcome. Hopefully this research will provide further insights into increasing the longevity of these panels at the same time as increasing their efficiency. Then polymer panels could potentially become the low cost, mass produced option enabling a new wave of investment to come from consumers who were previously locked out by current photovoltaic pricing.