Scientists have revolutionized solar cell technology with the development of a groundbreaking prototype that has the potential to become the most efficient solar cell in the world. This innovative design integrates multiple cells stacked into a single device, successfully capturing almost the entire solar spectrum and converting it into electricity with an impressive efficiency of 44.5 percent.
Unlike traditional solar panels seen commonly on rooftops or in fields, this new device employs concentrator photovoltaic (CPV) panels that utilize lenses to concentrate sunlight onto micro-scale solar cells. These cells, less than one millimeter square in size, can be developed cost-effectively due to their small dimensions. By acting as a sieve for sunlight, each layer of the stacked cell absorbs the energy of specific wavelengths, resulting in the conversion of just under half of the available energy into electricity. In contrast, current solar cell technology only converts a quarter of the available energy.
Lead author of the study, Matthew Lumb, explains, "Conventional materials for high-efficiency multi-junction solar cells cannot capture the entire spectral range of sunlight, which falls between wavelengths of 250 nm and 2500 nm. Our new device, however, has the capability to unlock the energy stored in the long-wavelength photons that are typically lost in conventional solar cells. This provides a pathway towards realizing the ultimate multi-junction solar cell."
This breakthrough approach incorporates two novel aspects. Firstly, it utilizes gallium antimonide (GaSb) substrates, which are commonly found in applications for infra-red lasers and photodetectors. These GaSb-based solar cells are assembled into a stacked structure alongside high-efficiency solar cells grown on conventional substrates that capture shorter wavelength solar photons. The stacking procedure is achieved through transfer-printing, a technique that enables three-dimensional assembly of these tiny devices with exceptional precision.
While the cost of this particular solar cell is currently high, researchers believe it is crucial to showcase the upper limit of efficiency that can be achieved. Despite the initial expense, the technique used to create these cells holds great promise. With advancements in technology and increased solar concentration levels, cost reductions and the ability to recycle the expensive growth substrates may eventually make this innovation economically viable.
The groundbreaking study, "GaSb-based Solar Cells for Full Solar Spectrum Energy Harvesting," was published in Advanced Energy Materials on Monday. By pushing the boundaries of solar cell efficiency, this research paves the way for a future where sustainable energy becomes even more accessible and affordable.