Breakthrough solar cells use indoor lighting

An international team led by University College London (UCL) has developed a more durable perovskite solar cell that can efficiently harvest energy from indoor light. The technology promises to enable low-power devices such as keyboards, remote controls, alarms, sensors, etc. to operate without batteries.

Unlike traditional silicon solar cells, perovskite can be tuned in composition to better absorb specific wavelengths of indoor light. However, the material often contains crystalline defects (called “traps”) that trap electrons, disrupting the flow of current and promoting degradation.

In the study published in Advanced Functional Materials , the team combined three chemicals to reduce this defect, including RbCl (rubidium chloride) which helps the perovskite crystals grow evenly and reduces stress, as well as two other chemicals that stabilize iodide and bromide ions, preventing them from separating and degrading performance.

"The solar cell has many defects, like a cake that has been cut into pieces. The three 'ingredients' we added joined the cake together, allowing the current to flow more easily. The combined effect is stronger than any of the individual components," explains lead author Siming Huang, a PhD student at UCL.

As a result, the cell achieved a conversion efficiency of 37.6% of indoor light at an intensity of 1,000 lux (equivalent to the brightness of an office), setting a world record for a perovskite cell optimized for indoor lighting with a bandgap of 1.75 eV. The expected lifetime is over 5 years, much higher than the weeks or months of previous models.

Testing showed that after more than 100 days, the new battery retained 92% of its initial performance, compared to 76% for the control sample. Under extreme conditions (300 hours of continuous high light at 55°C), the new battery retained 76% of its performance, while the control sample only had 47%.

Associate Professor Mojtaba Abdi Jalebi (UCL) said: "Billions of small power-consuming devices currently rely on battery replacement, an unsustainable practice. Our perovskite solar cells could capture more energy, last longer and cost less, because they are made from common materials, are simple to manufacture and can even be printed like a newspaper."