Swiss Researchers Achieve 30.22% Efficiency in Tandem Solar Cells

• EPFL’s groundbreaking tandem solar cell reaches 30.22% efficiency, merging perovskite and silicon innovations to redefine solar technology's future.

Researchers at the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland have developed an innovative perovskite-silicon tandem solar cell that achieved a remarkable efficiency of 30.22%. This advancement utilizes a heterojunction cell as the bottom layer, featuring double-sided micro-textured surfaces that enhance performance. The cell design circumvents previous challenges related to phosphonic acid film formation by implementing a self-assembled monolayer and optimizing the top cell's structure.

The tandem solar cell demonstrated impressive metrics during standard testing, including an open-circuit voltage of 1.954 V and a short-circuit current density of 18.92 mA/cm². The researchers noted that their approach holds significant potential for commercially viable tandem cells, effectively combining high-quality solution-processed perovskite top cells with textured Cz-silicon bottom cells. The findings underscore the capability of this design to achieve high efficiencies in solar technology.

How does the EPFL's tandem solar cell achieve its record efficiency of 30.22%?

• Innovative Composition: The EPFL tandem solar cell combines two types of materials, perovskite and silicon, which allows for better harnessing of the solar spectrum. The perovskite layer effectively absorbs higher-energy light, while the silicon layer captures lower-energy light, optimizing overall energy conversion.
• Heterojunction Technology: Utilizing a heterojunction structure for the silicon component enhances charge carrier mobility. This design minimizes recombination losses and contributes to the overall efficiency by ensuring that more of the absorbed sunlight is converted into usable electrical energy.
• Double-Sided Micro-Texturing: The integration of double-sided micro-textured surfaces improves light management within the solar cell. This design increases the surface area for light absorption, reduces reflection, and allows for better photon trapping, which results in higher current generation.
• Self-Assembled Monolayers: To address issues related to previous methods of film formation, researchers implemented self-assembled monolayers. These layers enhance the interface between the perovskite and silicon, improving stability and efficiency by facilitating better charge transfer and reducing defects at the junction.
• Optimized Top Cell: The structure of the perovskite top cell has been fine-tuned to enhance its performance. This includes adjustments in thickness, composition, and deposition techniques that maximize light absorption and improve the cell's overall efficiency.
• High Open-Circuit Voltage: Achieving an open-circuit voltage of 1.954 V indicates that the cell is effective at preventing charge recombination, allowing for a higher voltage output. This is crucial for maximizing the energy extracted from sunlight.
• High Short-Circuit Current Density: The short-circuit current density of 18.92 mA/cm² reflects the cell's ability to produce a significant amount of current under standard testing conditions, demonstrating efficient charge collection and transfer capabilities.
• Commercial Viability Potential: The combination of high-quality processed perovskite and textured Cz-silicon positions this tandem solar cell as a promising candidate for commercial applications. This could lead to wider adoption of advanced solar technologies in the renewable energy market.
• Future Research Directions: Ongoing research may focus on further enhancing material stability, scaling up manufacturing processes, and exploring integration with existing solar technologies to enhance overall system efficiency and lifespan.
• Environmental Impact: With the increasing demand for sustainable energy sources, the high efficiency of such tandem solar cells could significantly reduce the land area needed for solar installations, making them an environmentally friendly option for large-scale energy production.