
The researchers have applied an ultrathin layer of silver on this silicon substrate e.g. for solar cell electrodes. (Source: Marquard, RUB)
A new fabrication process for transparent ultrathin silver films has been developed by researchers at Ruhr University Bochum and the University of Wuppertal. The material may help build highly efficient solar cells and light-emitting diodes. However, traditional chemical methods have not been able to produce ultra-thin and pure silver films. A team headed by Anjana Devi and Nils Boysen from the Bochum-based research group inorganic materials chemistry, in collaboration with the group of Thomas Riedl from the chair of electronic devices in Wuppertal, developed the new synthesis method.
“Precursors for the fabrication of ultra-thin silver films are highly sensitive to air and light,” explains Boysen. The silver precursors can be stabilised with fluorine, phosphorus or oxygen. “However, these elements contaminate the thin films as well as the equipment used for the production,” continues the researcher. Boysen and his colleagues developed an alternative solution to tackle the problems associated with common silver precursors.
The researchers created a chemical silver precursor, where the silver is surrounded by an amide and a carbene, which is even stable without elements like fluorine, phosphorous or oxygen. They demonstrated that a silver thin film can be applied to an electrode with the new precursor by atomic layer deposition. In the process, the gaseous precursor is transported to the electrode and a silver film is deposited there as a layer with a thickness of merely a few atoms. Because it is so thin, the silver film is transparent. “As the process can be operated under atmospheric pressure and at low temperatures, the conditions for industrial production are quite favourable,” says Devi.
Following a series of tests, the researchers showed that the thin silver films manufactured using this method are pure and electrically conductive. “As far as process technology is concerned, the successful synthesis of the new precursor paves the way for the development of ultrathin silver films,” concludes Riedl. “It constitutes a first step towards the production of novel electrodes for highly efficient solar cells and lights.” (Source: RUB)
Link: Inorganic Materials Chemistry (A. Devi), Ruhr University Bochum, Bochum, Germany
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