- Researchers demonstrate revolutionary nanotechnology that significantly increases the efficiency of solar cells.
- It enables solar cells to capture infrared light and transform it into usable energy.
- Solar panels equipped with this technology could be 20-25% more efficient.
Invisible infrared light accounts for more than half of all solar radiation on Earth. In particular, sunlight at Earth’s surface is about 52% infrared, 42% visible, and 4% ultraviolet.
Infrared light is electromagnetic radiation with wavelengths (above 700 nm) longer than those of visible light (400 to 700 nm). Until now, modern solar panels haven’t been able to efficiently convert this region of light into power.
Recently, researchers at KTH Royal Institute of Technology demonstrated revolutionary nanotechnology that can significantly increase the efficiency of solar cells. They created a new kind of film that would enable conventional solar cells to capture infrared light and transform it into usable energy.
Nanoparticles Offer The Solution
In recent decade, solar energy has become the most popular source of renewable energy. Modern solar cells use photosensitive materials such as the mineral perovskite to convert light into energy. These materials, however, cannot properly respond to infrared light.
In this study, researchers focused on a unique class of optical nanomaterials doped with lanthanide ions: upconversion nanoparticles (UCNPs).
These nanoparticles can convert the spectral energy in the infrared range into a shorter-wavelength infrared and visible range. This could reduce the transmission loss in photovoltaic devices.
Recent advances in upconversion nanochemistry have enabled high-quality UCNPs with high luminescence quantum efficiency. But since these nanoparticles also have high excitation-intensity threshold, most of their light-converting capacity is wasted when incorporated into solar cells.
The research team found a solution to this problem. They utilized polymer-based microlens arrays to spatially modulate the excitation light. This helped them transform weak infrared radiation into visible light, at wavelengths the solar panels can convert.
A magnified view of the film that combines nanocrystals and microlenses to capture infrared radiation and transform it into usable energy | Courtesy of researchers
More specifically, researchers found that a part of polymer-based microlens array can concentrate excitation light by several orders of magnitude (depending on its optical and structural properties), leading to a significant enhancement of upconversion luminescence.
The microlens can be easily incorporated into various UCNP-enhanced photonic equipment, including dye-sensitized solar cells.
Researchers were able to achieve a 10% increase in solar cells’ efficiency without yet optimizing the technique. The efficiency can be further improved in the near future. They hope to achieve 20% – 25% more efficiency than what existing solar cells deliver.
The approach is general and can be merged with other techniques (photonic or chemical) of enhancing upconversion luminescence.