Solar cells can now be embedded into pictures or text thanks to a new inkjet printing method.
Developed by Aalto University, Finland, the system uses photovoltaic ink to absorb light which in turn generates heat that is then converted to electricity.
The darker the colour, the more electricity is produced, with pitch black therefore producing the most efficient solar cell.
Solar cells have already been manufactured for some time from inexpensive materials using different printing techniques.
Organic and dye-sensitized solar cells are particularly suitable for printing and the new process allows solar cells to be colourful, patterned and therefore used on the same surface as visual information and graphics.
“We wanted to take the idea of printed solar cells even further and see if their materials could be inkjet-printed as pictures and text like traditional printing inks,” said Janne Halme, who worked on the project.
“For example, installed on a sufficiently low-power electrical device, this kind of solar cell could be part of its visual design and at the same time produce energy for its needs.”
With inkjet printing, the photovoltaic dye can be printed to a shape determined by a selected image file and the darkness and transparency of the different parts of the image can be adjusted.
“The inkjet-dyed solar cells were as efficient and durable as the corresponding solar cells prepared in a traditional way,” said postdoctoral researcher Ghufran Hashmi. “They endured more than one thousand hours of continuous light and heat stress without any signs of performance degradation.”
The developers of the process spent a long time finding suitable solvent for the dye and the right jetting parameters in order to give the cells precise and uniform print quality.
The dye and electrolyte that turned out to be best were obtained from a research group in the Swiss École Polytechnique Fédérale de Lausanne.
The developers said the project could open up new possibilities for the development of decorative products and allow solar cells to be embedded directly into buildings.
South Korean scientists demonstrated ultra-thin photovoltaics in June that are flexible enough to wrap around a pencil and could be used in wearable electronics, such as fitness trackers and smart glasses in the future.