The most prestigious scientific journal Nature Energy published an article by German scientists on the development of a technology for the scalable production of today’s most advanced perovskite solar cells. We are talking about a fully perovskite tandem solar cell, both layers of which contain the crystalline structures of only these minerals. This means that such elements can be produced simply and quickly without losing a fairly high efficiency.
Tandem solar cells allow cells to operate over a wider energy spectrum. For example, the upper silicon layer absorbs red and infrared spectra, while the lower perovskite layer absorbs blue and green. Last week, such tandem perovskite cells set a record for efficiency, when the efficiency of photovoltaic cells exceeded 30% for the first time in history (for a cell of 1 cm2, which is important, since efficiency decreases with increasing scale). The result is amazing, although it should be remembered that one of the layers of this element is silicon with all the ensuing production features, including expensive processing.
In a new study, scientists at the Karlsruhe Institute of Technology (KIT) set out to create a tandem cell exclusively from perovskite minerals with different band gaps, which would allow the upper and lower layers of the cell to work with different spectra and avoid the use of silicon. The result was so good that the scientists called the development a direct path to the mass production of tandem pure perovskite cells.
Using a combination of mechanical application of solutions and vacuum deposition, the researchers created a cell that, with a net area of the photocell of 12.25 cm2 (excluding frames and contact electrodes), showed an efficiency of 19.1%. In the manufacture of the same element with an area of 0.1 cm2, the efficiency was 23.5%. The multiple scaling of the manufacturing process resulted in only an incomplete 5% drop in efficiency. This means that the process technology can be scaled up to mass without significant loss of efficiency. At the same time, the main advantages of the production of perovskite cells are retained – processing using liquid solutions and, as a result, the ability to create photovoltaic surfaces of complex shapes and on a flexible substrate.
Image Source: Bahram Abdollahi Nejand, KIT
Source: Karlsruhe Institute of Technology. The research is freely available from Nature Energy at https://rdcu.be/cRW93.