Solar cells are capable of efficiently harnessing energy from indoor light. Keyboards, remote controls, alarms, sensors, and all other devices could soon be battery-free.
The research at University College London (UCL) has concluded with the development of a new range of solar cells, perovskite solar cells. Perovskite, the material which used in the product development, is normally used in outdoor solar panels.
The composition inside the cells is kept flexible so as to better absorb the specific wavelengths of indoor light.
In terms of efficiency, the team claims that the perovskite photovoltaics are about six times more efficient than the other best available indoor solar cell options. They are optimistic about their durability compared to other perovskite devices. The life of new solar cells is expected to be five years or more, not just weeks.
Testing And Experiment Outcome
The researchers have achieved a world record for indoor light conversion efficiency, with their solar cells transforming 37.6% of light at 1,000 lux, about the brightness of a well-lit office, into electricity. These cells were specifically tuned for indoor use, featuring a 1.75 eV bandgap.
The team revealed that long-term stability tests revealed impressive durability. The optimized cells maintained 92% of their initial efficiency even after 100 days, while the untreated control devices held onto just 76%. Under extreme conditions, 300 hours of continuous high-intensity illumination at 55°C, the engineered cells still preserved 76% of their output, compared to only 47% for the control devices.
The only key limitation, as per the research team, of perovskite lies in microscopic flaws in the form of tiny defects within its crystal lattice, called traps. Traps can capture electrons before they harness energy. This flaw hinders electrical flow and accelerates the material’s long-term deterioration.
However, researchers incorporated rubidium chloride, which promoted more uniform crystal growth with minimal internal strain, significantly lowering trap density.
They also introduced two additional chemicals to stabilize iodide and bromide ions. This helped in preventing them from separating and clustering into different phases, a process that otherwise undermines solar cell performance by impeding smooth charge flow over time.
These steps contributed in making perovskite indoor solar panels viable.
Lead author Siming Huang, said, “The solar cell with these tiny defects is like a cake cut into pieces. Through a combination of strategies, we have put this cake back together again, allowing the charge to pass through it more easily. The three ingredients we added had a synergistic effect, producing a combined effect greater than the sum of the parts.”