Solar cell material that can absorb light during the day and emit light at night
When looking for the best materials with which to construct a solar cell, the obvious preference would be for one that absorbs light, not emits it. But researchers from Nanyang Technological University in Singapore have discovered a material that does both. Amongst a variety of potential applications, the researchers say the material, Perovskite, opens up the possibility of mobile devices with displays that double as solar cells.
Perovskite has already shown promise as a sunlight absorber, being used for this purpose in a prototype graphene-based photovoltaic device that achieved a record efficiency of 15.6 percent. The NTU team made the discovery that the material also emits light almost by accident when NTU physicist Sum Tze Chien asked his postdoctoral researcher Xing Guichuan to shine a laser on the new hybrid Perovskite solar cell material they were developing.
Because most solar cell materials are good at absorbing light, the team was more than a little surprised to see the Perovskite solar cell glow brightly when the laser was shone on it.
"What we have discovered is that because it is a high quality material, and very durable under light exposure, it can capture light particles and convert them to electricity, or vice versa," said Assistant Professor Sum. "By tuning the composition of the material, we can make it emit a wide range of colors, which also makes it suitable as a light emitting device, such as flat screen displays."
Because the Perovskite material can be made semi-translucent, the team says it could be used to create displays for mobile devices that would also charge up the device's battery in sunlight. On a larger scale, it could be used in tinted solar windows that generate electricity from sunlight during the day and become lighted displays at night. The researchers say that the highly luminescent Perovskite material is also suited to making lasers.
"Such a versatile yet low-cost material would be a boon for green buildings," says Assistant Professor Nripan Mathews from the School of Materials Science and Engineering (MSE) and the Energy Research Institute @ NTU (ERI@N). "Since we are already working on the scaling up of these materials for large-scale solar cells, it is pretty straightforward to modify the procedures to fabricate light emitting devices as well. More significantly, the ability of this material to lase, has implications for on-chip electronic devices that source, detect and control light."
The research team has filed a patent for the solar cell material and detailed its inner workings in a paper published in the journal Science.