For the energy transition to succeed, energy generation from renewable sources must become more efficient. Photovoltaic plants, for example, only convert some sunlight into electricity, the rest remains unused. However, new materials and substances mean that the yield from sunlight can be increased. BAM is providing important basic knowledge to this end.
Measuring the quantum yield
Certain substances can absorb light and subsequently emit it – these are known as self-radiating or photoluminescent. Special photoluminescent coatings are being tested for use in photovoltaics, for example, to increase the efficiency of solar panels. They absorb blue and UV light, which most solar panels are very inefficient at converting into electricity, and convert it into a spectral range that the solar panels are better able to use. The efficiency with which a substance can absorb and emit light is called its photoluminescence quantum yield. But how can this efficiency be determined?
BAM is developing reference materials
BAM researchers are developing reference materials for this. These are so efficient at absorbing and emitting light that they are used as standards. The researchers at BAM are drawing on the unique properties of the Ulbricht sphere to do this. The sphere enables the precise measurement of the quantum yield under controlled conditions. BAM uses this technology to identify the quantum yield of substances that are used in the production of efficiency-enhancing coatings for solar plants. The energy yield of a test plant rose by 0.5% as a result of the new coating. That does not sound like much, but in the context of around 1.5 million photovoltaic plants in Germany, it would be a significant increase in energy production.
Certification of substances and materials
Photoluminescent substances can be used in many other areas apart from photovoltaics, for example in medical and display technologies. BAM is currently working on new reference materials with certified quantum yields. The reference materials developed by a BAM research team led by Dr. Jutta Pauli should be available as early as 2017/18. Manufacturers will then be able to compare their new developments directly with BAM's reference materials and characterise and make their products safer in a traceable way. In this way, BAM is making an important contribution to the development of new and efficient optical technologies.