What is an Organic Solar Cell?
Conventional solar cells normally use hard silicon as the semiconductor to harvest light and convert it to electricity. The big difference with organic solar cells is that the semiconductor is plastic. Other components, such as the front and back conductors, can also be plastic, or very thin, flexible layers of metal and/or ceramic conductors. This means that organic solar cells can be very flexible. Organic solar cells are also called plastic- or polymer-based solar cells.
What are the Types of Organic Solar Cells?
One of the big advantages of organic solar cells is that light absorbers are available in a wide range of colours, rather than the traditional black of conventional solar panels. This is because there is a large range of different polymers that can be used to harness sunlight. The polymers absorb different wavelengths and thus appear as different colours. This gives them great potential to be integrated into buildings or other structures, perhaps alongside solar roof tiles. They can also be made partially transparent, expanding potential applications to areas like covers for greenhouses in agriculture. Transparency would also enable organic solar cell panels to work like bifacial panels – harvesting sunlight on each side.
The other big advantage is flexibility. Organic solar cells can be made incredibly flexible. Again, this makes them attractive for many structure-type applications. It also makes them suitable for wearable and portable products. Imagine being able to carry a light, rolled up solar panel wherever you go!
Manufacturing organic solar cells is potentially more economical due to the ability to use so-called roll-to-roll processing technology. This type of processing allows very rapid throughputs and is therefore potentially a very cheap method of production.
The manufacturing process is also low energy. Silicon is produced by very high temperature processing of silica (sand) whereas organic solar cells can be cast from a solution. This means the energy payback time (i.e. the time it takes for the solar panels to produce the same energy as went into making them) is potentially much shorter for organic solar cells. This is great for the environment.
Organic solar cells are also super easy to install. They can be simply rolled out and glued to most surfaces. Therefore installation costs, which are one of the major costs for solar panels, are much lower than conventional solar panels.
Unfortunately, whilst organic solar cells are ingenious inventions, there are a few negatives associated with their use.
Organic solar cells currently don’t have great lifetimes. The best cells last 10 years, which is encouraging but nothing like the 25 year lifetimes that have become the norm for conventional solar cells. This is a major area of research and development that is needed.
Efficiencies are also lower than conventional solar cells. The best efficiency recorded for an organic solar cell is 18% in the laboratory. Some efficiency is lost when moving to large scale modules, so that a practical efficiency is probably more like 15%. And that is the best result. Conventional solar cells are already commercially available near 22% efficient, and most solar panels in large scale production are higher than about 18% efficient. This is a big difference when considering energy output over the entire life of the system.
The global market for organic solar cells was about $55 million in 2019, and is predicted to grow to about $100 million in 2027.
The diagram below shows where the cells are currently being used. Building integrated photovoltaics (BIPV) is the main market segment. As mentioned previously, the variety of colours available and the flexibility make polymer-based cells attractive for building products.
These attributes also explain why the next biggest market is portable electronics. Organic solar cells offer a portable power solution for the ever-increasing range of portable electronics that our society craves.
Which Companies Produce Organic Solar Cells?
Unlike conventional solar cells that are mainly produced in China, organic solar cells are primarily produced in the US and Europe. This is a list of the major companies and their locations.
InfinityPV ApS (Denmark)
SolarFarmer Energy (US)
Nanoflex Power Corporation (US)
New Energy Technologies Inc (US)
Novaled GMbh (Germany)
Brite Solar (Greece)
Organic solar cells certainly offer lots of exciting possibilities with their lightness flexibility and range of colours. We will no doubt see more and more of them. And if their lifetimes can be improved, expect them to boom.
In normal solar cells, the semiconductor that converts sunlight to electricity is hard, solid silicon. In organic solar cells the semiconductor and other layers are flexible.
They are extremely flexible, lightweight and can come in a range of colours.
Organic solar cells have shorter lifetimes than conventional solar cells. Their efficiencies are also lower.
Yes! The current global market is about $55 million, expected to increase to $100 million by 2027.
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