Transparent Solar Cells With 30-Year Lifetimes

Researchers developed transparent organic solar cells with a 30-years lifetime for power-generating windows.

Solar energy is one of the cheapest sources of energy available today. Many researchers and engineers have conceptualized and imagined solar cells on windows of buildings. With solar cells on windows, the building can become a power plant. 

Silicon is the most widely used material in commercial solar cells due to its high efficiency. But silicon isn’t transparent, and therefore, researchers have been exploring organic carbon-based materials for windows. These materials are known generally as “non-fullerene acceptors” to set them apart from the more robust but less efficient “fullerene acceptors” made of nanoscale carbon mesh. Solar cells made with non-fullerene acceptors can achieve high efficiencies up to 18%, but they degrade quickly.

The degradation is due to weak bonds that easily dissociate under high energy photons, especially the UV (ultraviolet) photons common in sunlight. 

Researchers at North Carolina State University and Tianjin University and Zhejiang University in China aim to change this scenario. They demonstrated that without any protection from UV rays, the efficiency of the material fell to less than 40% of its initial value within 12 weeks.

The team recognized that they’d need to block out UV light, and for that, they added a layer of zinc oxide on the sun facing side of the glass. In addition, the electrode that draws holes into the circuit can also react with the light absorber. To protect that part, they added another buffer layer with a fullerene shape like a soccer ball.

The team validates their defenses against sunlight and extreme heat. They found out that the solar cells would still be running at 80% efficiency after 30 years. The team has already increased the transparency of the module to 40%. They believe they can approach 60% transparency. 

Moreover, they are also working on increasing the efficiency of these solar cells from 10% to 15%. 

The research has been published in the journal Nature Communications.

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