There is a third generation of solar cells made from organometallic compounds. While projects are still largely in the development phases, there has been a lot of investment recently into how to build a highly efficient organic cell at relatively low cost.
The ‘organic’ nature of the cells relates to the use of carbon materials instead of silicon at their core. Organic PVs are made from compounds that are dissolved in ink and are printed on thin rolls of plastic. These cells are much more pliable than solid silicon panels, meaning they can be bent around structures or incorporated into softer materials such as clothing.
The main issue with organic solar cells is efficiency – the measure of how much light energy can be transferred into electrical energy. Silicon solar cells typically have an efficiency rate of around 15%-22%, with the exception of some pioneering efforts such as Oxford PV, which set a record conversion rate of 27.3% in the UK last year.
However, conversion rates for organic cells have been generally much lower – at around half the efficiency of their silicon counterparts. That was the case until Henry Yan at the Hong Kong University of Science and Technology, in collaboration with North Carolina State University physicist Harald Ade, developed a PV made from organometallic materials that achieved 14.2% efficiency (the National Renewable Energy Laboratory certified this cell at 11.5% efficient). Yan did not submit his 14.2% efficient cell, stating it was not stable enough.
According to estimates, organic cells with a 20-year lifespan could produce electricity at a cost of less than 7 cents per kilowatt-hour (kWh). The average electricity cost in the US for 2017 was 10.5 cents per kWh, according to the US Energy Information Administration. That small reduction in cost could accumulate to a considerable saving for energy providers and consumers, not to mention the cash saving advantages of going organic.