Breakthrough: Tandem Organic Solar Cell Hits 16.94% Efficiency

Researchers at ICFO have recently achieved a major milestone in the field of solar energy with the fabrication of a new four-terminal organic solar cell featuring a tandem configuration. This innovative device boasts an impressive power conversion efficiency (PCE) of 16.94%. The key to its success lies in the incorporation of a highly transparent front cell equipped with a transparent ultrathin silver (Ag) electrode, measuring only 7nm in thickness. This electrode plays a crucial role in ensuring the efficient operation of the solar cell.

Two-terminal tandem organic solar cells have long been recognized as a promising solution for addressing transmission and thermalization losses in single-junction solar cells. By combining front and rear subcells with different bandgaps, these organic solar cells can achieve broader absorption and utilization of the solar spectrum. However, optimizing the performance of such configurations requires a delicate balance of current between the two subcells. Additionally, the fabrication of tandem organic solar cells poses challenges, as it necessitates a robust interconnection layer capable of facilitating efficient charge recombination while maintaining high transparency.

The emergence of the four-terminal tandem configuration represents a significant advancement in solar cell design strategies. In contrast to the two-terminal approach, this configuration features separate electrical connections for the transparent front cell and the opaque back cell. As a result, the issue of electrical current matching is no longer a limiting factor. This setup provides greater flexibility in selecting the bandgaps of each cell within the tandem, thereby optimizing photon absorption and ultimately enhancing the overall efficiency of solar energy production.

Francisco Bernal, a researcher at ICFO and the first author of the study, emphasized the importance of the transparent silver intermediate electrode in the efficient operation of the solar cell. According to Bernal, the electrode must strike a delicate balance between transparency and electrical conductivity to ensure optimal performance of the front cell. The ability to fabricate such an electrode with a thickness of only 7nm represents a significant breakthrough in the development of transparent solar cells.

In conclusion, the successful fabrication of the new four-terminal organic solar cell with a tandem configuration marks a significant step forward in the quest for more efficient and sustainable solar energy technologies. With its high power conversion efficiency and innovative design features, this solar cell holds great promise for the future of renewable energy production. The research conducted by ICFO paves the way for further advancements in the field of organic solar cells and underscores the importance of ongoing innovation in renewable energy technologies.