06/04/2024
Act. at 08:14
CEST
The efficiency of the solar cells that make up the photovoltaic panels It is getting better and better. Now, researchers from the Federal Polytechnic School of Lausanne (EPFL), in Switzerland, have achieved a new and very significant advance in this field. Specifically, they have developed a double-layer photovoltaic cell with a 30.9% conversion performance, almost the maximum possible. This would allow a very important improvement in the use of energy from the Sun.
It must be taken into account that photovoltaic panels convert only part of the light energy they capture from the Sun into electricity. The maximum theoretical efficiency of these panels is 31%although the most efficient among those commonly marketed, the monocrystalline ones, have an efficiency that does not usually exceed 24%.
What is this maximum due to? This limitation is a consequence of the panels’ inability to convert high-energy photons, which restricts their effectiveness.
The novelty: ‘tandem’ cells
In order to overcome this limitation, EPFL scientists have developed “tandem” photovoltaic cells. These cells They are composed of two different layers that significantly improve energy conversion performance.
The top layer is made of perovskite, a material that allows for the efficient absorption of high-energy photons in the light spectrum. The bottom layer is made of silicon and is responsible for converting red and infrared light.
The upper layer perovskite is treated with 2,3,4,5,6-pentafluorobenzylphosphonic acid (pFBPA), which improves cell efficiency and solves lead-related problems. This treatment, combined with a SiO2 nanoparticle-coated substrate, reduces pinhole formation and shunt resistance, thus optimizing the cell’s conversion capacity.
Furthermore, the top layer includes a substrate composed of indium tin oxide, silicon dioxide nanoparticles, perovskite, buckminsterfullerene, phosphonic acid, silver, and indium zinc oxide. These materials were selected and combined to maximize energy absorption and conversion efficiency.
The results achieved
During tests carried out by the researchers under normal lighting conditions, the tandem photovoltaic cell achieved a conversion efficiency of 30.9%. These results have been certified by an entity competent in the matter, whose name has not been revealed, which would ensure the validity of the data obtained. The use of pFBPA, in particular, has been fundamental to this optimization.
One of the main challenges in the design of the tandem cell was the optimization of the perovskite layer to make it sufficiently permeable to light, thus allowing the efficient conversion of both high-energy photons and red and infrared light. The researchers achieved this by replacing the traditional gold coating on the electrodes with materials based on metal oxides, which are conductive and allow approximately 80% of light energy to pass through.
Additionally, the bandgap of the bottom layer was adjusted to improve its ability to convert light energy into electricity, thereby aligning the cell design with existing industrial processes to keep production costs low.
Revolution in solar energy
EPFL scientists’ progress in developing tandem photovoltaic cells represents a significant step towards improving the efficiency of solar panels. With a conversion efficiency of 30.9%, these cells could transform the field of solar energy, making renewable energy more efficient and accessible.
The integration of these advances into existing industrial production also promises a reduction in coststhus encouraging wider and more sustainable adoption of solar energy.
This development not only brings solar technology closer to its theoretical limit of efficiency, but also marks an important milestone on our path towards a greener, more sustainable future.
Reference study: https://www.sciencedirect.com/science/article/pii/S2542435124001995
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