Industrial production of silicon perovskite tandem solar cells comes closer
Only a few years ago, solar cells made of perovskite materials with efficiencies of around 10 % achieved only a meager energy yield. Today, the latest cells impress with an efficiency more than twice as high. Research groups at the HZB have been instrumental in this rapid and significant improvement of cell characteristics. This novel tandem solar cell consists of a silicon cell and a second, superimposed cell based on a semiconductor compound with perovskite structure. The advantage of combining different materials: their absorption spectra complement each other. This means that tandem solar cells can significantly exceed the physical limit of 29.4 percent efficiency of the silicon solar cells used today.
Now the scientists at HZB want to go one step further. The goal of Prof. Dr. Bernd Stannowski from the Photovoltaics PVcomB Competence Center at HZB is to increase the efficiency of such cells by more than 30 % – not only on a laboratory scale, but also when produced on a commercial scale. The researchers are relying on modular systems that will raise the production of silicon-perowskite tandem solar cells to an industry-relevant level. This will make it possible to produce tandem cells on 6-inch wafers, as is common in the photovoltaic industry.
For the lower part of the tandem solar cells, the so-called bottom cell, a silicon heterojunction is the structure of choice, whereby the surfaces of the silicon wafer are provided with very thin amorphous silicon contact layers. These are produced by deposition using Plasma-Enhanced Chemical Vapour Deposition (PECVD). For this purpose, HZB researchers have access to a cluster facility of the Swiss company Indeotec. The system is characterized by a technical novelty: “It is the first system of its kind in the world to feature PECVD mirror process modules that allow silicon wafers to be coated on both sides – without having to rotate them.
The bottom cell produced in this way serves as the basis for further processing into a tandem solar cell. For this purpose, the HZB team in the Innovation Laboratory for Research on Hybrid Silicon-Perovskite Structures (HySPRINT) will be able to use a new facility for the vacuum deposition of various materials financed by the German Federal Ministry of Economics and Energy from 2021. It is being developed by the Dresden-based companies Von Ardenne and Creaphys specifically for this purpose. The recently ordered new plant will integrate all necessary process steps for the production of the upper cell made of perovskite.
“With this technology, which is unique in the world, the complete cell, consisting of several layers, as well as the electrical contacts can be produced automatically and in a single pass at high throughput,” emphasizes Stannowski. This will bring the commercial production and use of silicon-perovskite tandem solar cells a big step closer, according to the Berlin researcher.
More information: https://www.helmholtz-berlin.de/projects/pvcomb/index_en.html
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