Artificial light is different from sunlight. Above all, it is not efficiently converted into electricity by solar modules. A new type of perovskite solar cell is set to change this thanks to its high efficiency.
Smaller spectrum, less energy, hardly any infrared radiation: photovoltaics only work to a very limited extent behind window panes and even more so in the evening when LEDs or light bulbs are switched on.
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| Light indoors is structured differently than outdoors, so the solar cell must also be designed differently. (Image source: pixabay/pruzi) |
On the other hand, smart sensors, digital clocks and many other small devices with low power requirements are located right there: in the house, on the desk, on the shelf, on the wall. These could be used without a power connection and without changing batteries, even without battery, if the artificial light that is almost always available could be converted back into electricity.
This would require an inexpensive, efficient solar cell that can handle the limited light spectrum. And this is exactly what a research group from the University of Kaunas, Lithuania, has just presented it.
Organic semiconductor plus perovskite
With the combination of an organic semiconductor and perovskite, the remarkable efficiency of 37 percent for the conversion of light into electricity was achieved despite adverse conditions - for a photocell.
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| Thiazol[5,4-d]thiazoles are very effective at converting room light back into electricity - TTP-DPA is the best. (Image source: ACS Applied Materials and Interfaces) |
The light source used in the experiments was a warm white LED. The light temperature of 3,000 Kelvin used corresponds to the typical choice for living rooms. The spectrum is similar to that of natural light, but without infrared radiation, which is not visible.
The solar cell developed consists of a layer of perovskite, and a special compound of thiazole molecules is used to conduct positive charges. Thiazoles are aromatic compounds with nitrogen and sulphur embedded in their hydrocarbon rings.
They are linked together to form complex structures that performed differently in the experiments. In this way, the exact structure could be determined in order to achieve an impressive 37 percent efficiency with the light of a standard LED. A comparison with the performance in sunlight shows how strong the adaptation to interiors is. Here, the efficiency is only 19 percent, which is below that of a commercial solar system.
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