New research conducted by a team of Chinese scientists has created the thinnest silicon solar cells ever: a flexible, paper-like material that converts light into electricity without sacrificing efficiency and with great lightness.
Silicon solar cells are the backbone of solar-generated electricity in the world and account for approximately 95% of solar cells in the photovoltaic market. As energy production and generation costs have fallen, solar cells have found wider use in ground-mounted solar parks and distributed photovoltaics.
Last Monday, state-run newspaper Science and Technology Daily quoted Li Yang, a professor at Jiangsu University of Science and Technology (JUST), as saying that crystalline silicon solar cells, made from silicon wafers, are the most mature technology and more widespread for the production of photovoltaic energy, “but they face two main technological bottlenecks”.
One disadvantage is that the energy conversion efficiency of large silicon cells remains limited to 26%; the other obstacle is the thickness of the cells – typically 150 to 180 micrometers (0.15 mm to 0.18 mm), which makes it difficult to use in applications that require a more flexible and lightweight material, such as curved roofs , satellites and space stations.
Aircraft, for example, have extremely stringent weight requirements and have used thin-film solar cells, another broad category of solar cells. However, according to Li, they are expensive, have a short lifespan and are not suitable for commercial needs.
The flexible silicon solar cells developed by Li and his collaborators are much thinner and lighter than their conventional counterparts and boast high energy efficiency. “We have developed crystalline silicon cells as thin as 50 micrometers – thinner than an A4 sheet of paper – that can be folded into a roll and are much more efficient than conventional ones,” Li said. To give you an idea, 50 micrometers is 0.05 millimeters
The research, published in the journal Nature on January 31, was the result of joint work by scientists from JUST, the LONGi Green Energy Technology company in Xian and Curtin University in Australia.
Crystalline silicon solar cells are known as a “sandwich” structure, meaning the wafer substrate – the middle layer – represents more than 99% of the cell thickness. Scientists around the world have used different approaches to develop lighter, more flexible, highly efficient and commercially viable solar cells.
But the China-led team took the subtlety even further. “Wafer thinning not only reduces the weight and cost [of solar cells], but also facilitates charge migration and separation,” the Nature paper reads.
However, getting thinner and thinner wafers has always come at a cost in terms of efficiency: thinner silicon solar cells have always been less efficient at converting sunlight into electricity than thicker ones.
In a paper published in the same issue, the authors said that previous thin crystalline silicon cells – less than 150 micrometers thick, produced using conventional techniques – had power conversion efficiency (PCE) ranging from 23.27 at 24.7%.
Instead, the JUST team managed to solve the wafer problem while maintaining a yield of 26%, in line with what is possible from the best single-state crystalline silicon cells, i.e. without the addition of pyrovskite layers.
These ultra-thin solar cells are also bendable. “They can't be bent in half, but they can be bent into any curvature,” Li said, adding that this feature would greatly expand the range of applications of crystalline silicon cells.
Flexible solar cells have many more application possibilities, including use in aerospace, airships, drones and wearable smart devices, or simply covering curved surfaces. They would be incredibly lighter and potentially less expensive.
Li said researchers are working to develop more flexible and efficient crystalline silicon cells that could one day be as portable as a roll of film.
This is a machine translation of a post published on Scenari Economici at the URL https://scenarieconomici.it/scienziati-cinesi-realizzano-celle-fotovoltaiche-al-silicio-spesse-un-ventesimo-di-millimetro-e-pieghevoli/ on Sun, 11 Feb 2024 06:15:19 +0000.