Scientists at Case Western Reserve University that have been experimenting with the use of small perovskite solar cells to help recharge the batteries of electric cars state that they have found a system that performs better than any other. They wired four perovskite solar cells in series to directly photo-charge lithium batteries with 7.8% efficiency.

The researchers say that they have found the right match between the solar cell and battery. The coupling appears to have outperformed all other reported pairings of photo-charging components and compatible batteries or supercapacitors. They have created cells with three layers converted into a single perovskite film and then wired four of the 1 mm square cells in series, achieving a solar-to-electric power conversion efficiency of 12.65%. When hooked up to charge small coin-sized lithium-ion batteries, the team achieved a conversion and storage efficiency of 7.8% and maintained it over a number of cycles.

The scientists' vision is of a system that can be kept at home to refuel cars and, eventually, because perovskite solar cells can be made as a flexible film, they would be on the car itself. The advantage provided by the perovskite cells is that they allow recharging a battery without disrupting the styling of a car too much, unlike large solar panels more commonly associated with solar powered cars.