Perovskite solar cells have gained a lot of attention in research circles recently owing to significant and relatively fast leaps in its efficiency, but the toxic lead they contain is something engineers would rather do without. There are alternatives in the works, and scientists have just uncovered a new use for these safer and greener types of light absorbers, finding that they can harvest energy from indoor lighting with impressive efficiency.
The research was carried out by scientists in China and the UK and focuses on what are known as lead-free perovskite-inspired materials (PIMs), which are under development for use in next-generation solar cells. These are similar in structure to typical lead-halide perovskites but don’t contain the same toxic ingredients. This makes them safer, but does come at a cost as these types of materials don't absorb sunlight with the same efficiency.
As it turns out, the first place they may prove useful is in indoors. The team took a pair of “exemplar” PIMs and investigated their performance under indoor lighting conditions, through which they found that, while the bandgaps are too wide to excel in solar applications, they were almost perfect for indoor light harvesting.
According to the researchers, the PIMs were able to perform with an efficiency of around 1 percent under sunlight, but this increased to four or five percent under indoor lighting. While this is a far cry from some experimental indoor perovskite solar cells, the scientists say this is on par for the current industry standard for indoor photovoltaics. They were able to demonstrate that millimeter-scale PIMs could draw enough energy to power thin-film transistor circuits, but the potential doesn’t end there.
“By efficiently absorbing the light coming from lamps commonly found in homes and buildings, the materials can turn light into electricity with an efficiency already in the range of commercial technologies,” says co-author Dr Robert Hoye from Imperial College London. “We have also already identified several possible improvements, which would allow these materials to surpass the performance of current indoor photovoltaic technologies in the near future.”
The team imagines one day putting these types of materials to use in all kinds of ways, drawing on light from lamps and indoor bulbs to power phones, speakers, wearable devices and sensors. There is a lot more research and development to take place before any of the happens, but the breakthrough opens up some interesting new possibilities to pursue.
“In addition to their eco-friendly nature, these materials could potentially be processed onto unconventional substrates such as plastics and fabric, which are incompatible with conventional technologies,” says co-author Professor Vincenzo Pecunia from Soochow University. “Therefore, lead-free perovskite-inspired materials could soon enable battery-free devices for wearables, healthcare monitoring, smart homes, and smart cities.”
The research was published in the journal Advanced Energy Materials.
Source: Imperial College London
