Perovskite solar cells already show efficiencies of over 25 per cent in the laboratory. At the same time, they have cheaper raw materials and simpler production methods than similarly efficient silicon cells. However, this is still only true on a small scale: "In addition to stability, a central hurdle for the market entry of the technology is to transfer the high efficiency achieved on small surfaces to large surfaces," says Professor Ulrich W. Paetzold from the Institute for Microstructure Technology (IMT) at the Karlsruhe Institute of Technology, KIT for short. Only in this way, however, can the technology lead to the development of cost-efficient solar modules.
Colouring by inkjet printing
Because aesthetics play an important role for such a use in addition to costs and efficiency, Paetzold's research team, together with the industrial partner Sunovation, investigated an inkjet printing method that can colour perovskite solar modules. The advantage: colouring the modules by inkjet printing is cost-effective and also suitable for larger areas.
See also: HZB achieves 30 per cent efficiency with perovskite-silicon tandem
"Until now, when producing coloured perovskite solar cells, the colour impression of the solar cell for the observer was strongly dependent on the angle of the incident light," explains project coordinator Helge Eggers from IMT. "With our method, on the other hand, the colour used is almost not at all dependent on the angle of incidence of the sunlight, but always looks the same," Eggers describes. In a series of experiments, the researchers were able to prove that this method, originally developed for solar modules made of silicon, also works for perovskite solar modules. The solar cells, vividly coloured in the base colours cyan, magenta and yellow, showed up to 60 per cent of the original efficiency when converting solar energy into electricity.
Colour mixing enables marble look
Inkjet printing technology also makes it possible to print complex colour patterns. The researchers used this to produce solar modules in the look of various building materials. Perovskite solar modules with a white marble look proved to be particularly efficient. Here, the team was able to achieve efficiencies of up to 14 per cent.
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"The goal of building-integrated photovoltaics is not to mount photovoltaic systems on roofs or facades, but to replace them with modules and thus avoid additional costs," says Eggers. "For in-building photovoltaics, an integrated solar cell with low efficiency is better than a wall that delivers no electricity at all." (nhp/mfo)
