A patented Technion breakthrough improves the efficiency of organic photovoltaic cells by 50 percent, and could someday provide a huge boost for the viability of solar power as a major source of energy. The researchers published their findings in the Journal of Applied Physics.

Organic photovoltaic cells convert solar energy into electric power through organic molecules. One advantage over “traditional” solar cells made of silicon is that they can be mounted on lightweight, flexible, and easy-to-replace sheets, which can be spread on roofs and buildings like wallpaper, converting solar energy into electrical current. In the future, they could also be used to provide a cost-efficient and reliable source of electricity in isolated regions.

Despite the advantages of organic cells, their power conversion potential to this point has not been fully utilized, according to lead researcher Prof Nir Tessler, of the Viterbi Faculty of Electrical Engineering, and Head of the Wolfson Microelectronics Centre and the Sara and Moshe Zisapel Nanoelectronics Center.

“In our study, we found that the electricity production and efficiency of organic photovoltaic cells are limited by structural aspects,” explains Tessler. “We have proved that these limitations are not related to the material, but to the device structure. We have developed an addition to the existing systems, improving the efficiency of converting solar energy into electric current inside the cell from 10% (a level considered to be “high efficiency”) to 15% (the level at which industry experts say organic solar cells will be cost effective), and adding 0.2 volts to the cell’s voltage.

”The development is based on increasing the energy gap between the electrodes by changing their fixed position in the system. By doing so, the researchers were able to increase the voltage, leading to an increase in system power. “This improvement is significant for the relevant industry, and it was achieved by focusing on structural changes in the device, versus developing new materials, a common approach by researchers in this field. It might seem as if we have stretched the laws of physics with the aid of engineering.”

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Prof. Nir Tessler
Prof. Nir Tessler