Researchers Make Strides in Creation of Transparent Solar Cells

Researchers have developed a highly transparent organic solar cell they say could one day pave the way toward the widespread use of the clean, renewable source of energy.

While the wafer-based silicon solar cells used in many of today's commercial solar panels are relatively efficient in converting solar radiation into electrical power, they face a number of obstacles in terms of maximum exploitation, such as precise alignment in order to receive direct sunlight. They are also heavy, opaque and bulky.

Organic solar cell technology isn't new, dating back some 30 years, neither are organic cells as efficient as their silicon based counterparts. However, low production cost has begun to attract more and more interest, as have the advantages of Organic Photovoltaic (OPV) cells, including increased flexibility, relative transparency and sensitivity to low light levels and indirect sunlight.

When it comes to OPVs and transparency, it's a compromise. To turn the cells transparent, the black metal electrode has to be reduced to just a few nanometers, limiting its ability to collect sunlight.

To address this issue, researchers from the Institute of Photonic Sciences (ICFO) have implemented a semi-transparent cell using a photonic crystal in order to achieve performance levels as good as the opaque ones. Furthermore, by using the photonic crystal, the cell's ability to absorb infrared and ultraviolet light increased -- all with a device almost indistinguishable from regular glass in terms of transparency.

According to lead author Jordi Martorell, the technology is still "a few steps away" from application.

However, Martorell notes: "ICFO's discovery opens the path for innovation to other industrial applications of transparent photovoltaics. In the midterm we expect to reach the extremely high transparencies and efficiencies needed to power up devices such as displays, tablets, smart phones, etc..."