A new technology that could improve the efficiency of photovoltaic cells by almost 70% has been developed by researchers at the Technion Israel Institute of Technology.
The breakthrough could be used to overcome the limitations of current technologies for harnessing solar power in order to meet the world’s growing energy demands. Photovoltaic cells only use a very narrow range of the broad light supplied by the sun. Radiation that is outside this narrow range is not used and simply serves to warm up the cells. This limits the maximum efficiency of current solar cells to about 30%.
In an article recently published in Nature Communications, the Technion team explain how their technology is based on an intermediate process that occurs between the photovoltaic cell and sunlight. The photoluminescence material created by the team absorbs most of the radiation from the sun. The heat and light from the sun is then converted into an “ideal” radiation, which lights up the photovoltaic cell, resulting in a higher conversion efficiency. The device’s efficiency is increased from 30% to 50% as a result.
Optical refrigeration technology re-emits the absorbed light at higher energy, thereby cooling the emitter. The Technion was inspired by this technology, but uses sunlight instead.
Graduate student Assaf Manor led the study as part of his PhD work. He explained that solar radiation hits a dedicated material that they developed for this purpose on its way to the photovoltaic cells. The unused part of the spectrum heats the material. The solar radiation in the optimal spectrum is also re-emitted at a blue shifted spectrum once it has been absorbed. The solar cell then harvests this radiation and both the light and the heat are converted to electricity.