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