Efficient perovskite solar cells replace disposable batteries in indoor devices

A research team from University College London (UCL), in collaboration with Chinese and Swiss scientists, has developed a perovskite-based solar cell for indoor use that is up to six times more effective than previous indoor solar cells. Existing artificial light indoors could be used to power remote controls, smoke detectors, and sensors, for example, so that they no longer require disposable batteries.

Current indoor solar cells still have many negative characteristics. Above all, they are expensive and inefficient. This makes them unsuitable for mass application. However, there are enough areas of application where artificial light can be used to supply smaller electronic devices with electricity via solar cells. This could solve the problem of masses of disposable batteries in private households, offices, and production facilities.

The research team uses perovskite as the starting material for their solar cells. Perovskite is a fairly common mineral and therefore inexpensive. It has already shown promise for outdoor solar systems as long as it does not have any structural defects. Compared to silicon conventionally used for solar cells, the mineral can be grown to absorb certain wavelengths of light. This makes it more suitable for use in areas with less light than silicon-based solar cells.

Improving perovskite crystals

The problem with perovskite solar cells, however, is that the material can have small defects in its crystal structure, called traps, which can impede the flow of the electrodes. However, the researchers found a solution to this, as they write in the study “Enhancing Indoor Photovoltaic Efficiency to 37.6% Through Triple Passivation Reassembly and n-Type to p-Type Modulation in Wide Bandgap Perovskites,” which was published in Advanced Functional Materials.

They added rubidium chloride when growing the perovskite crystals. This made it possible to achieve more uniform growth of the crystals and reduce the number of traps. But this was not enough for the scientists. To stabilize the ions of the material and prevent them from splitting, they added two organic ammonium salts: N, N-dimethyloctylammonium iodide (DMOAI) and phenethylammonium chloride (PEACl). Both ensure that efficiency is less impaired.

More efficient solar cells

Using the modified perovskite material, the researchers created indoor solar cells that can convert 37.6 percent of the light at around 1000 lux in bright rooms into electricity. According to the researchers, this is six times better than the best indoor solar cells currently available on the market.

The researchers put their perovskite cells through various stress tests. After 100 days, the cells still had 92 percent of their output, compared to only 76 percent for conventional perovskite cells. From this, the scientists calculated a potential service life in small electronic devices. The solar cells could supply such devices with energy for up to five years.

The researchers are convinced that their modified perovskite solar cells can be used indoors. Talks are already underway with potential industrial partners to enable commercial use and mass production.

(olb)