In the sterile, LED-lit gloom of an office, a solar panel is about as useful as a sundial. Traditional silicon cells are built for the unfiltered fire of the Sun but work miserably with artificial light. Yet billions of small devices — remote controls, alarms, wireless sensors — live their entire lives under ceilings. They have to be powered by disposable batteries, each a tiny packet of mined metals destined for the landfill.

Now, researchers at University College London and their collaborators have engineered a new class of indoor solar cell that doesn’t just work under artificial light — it thrives. Their device turns 37.6% of the light in a well-lit room into usable electricity, a world record for this type of technology. That’s roughly six times better than the best commercial indoor cells. And unlike earlier prototypes, it lasts not weeks or months, but years.

The secret lies in perovskite, a crystalline material whose atomic lattice can be tuned to sip from the specific wavelengths emitted by LEDs and fluorescent bulbs.

“Currently, solar cells capturing energy from indoor light are expensive and inefficient,” said Dr. Mojtaba Abdi-Jalebi, associate professor at the UCL Institute for Materials Discovery. “Our specially engineered perovskite indoor solar cells can harvest much more energy than commercial cells and is more durable than other prototypes.”

The Perovskite Trap

Experts hail perovskites as the future of solar energy. They cost less, offer more versatility than silicon, and can be printed like newspaper ink. They’re already pushing efficiency limits in outdoor solar panels. But indoors, they’ve faced a fundamental flaw.

Tiny defects, called “traps,” lurk deep inside the crystal structure of perovskite, snagging electrons and draining their energy as heat. These traps also contribute to the material breaking down over time.

Dr. Abdi-Jalebi’s team tackled this challenge with a triple-chemical treatment. First, they introduced rubidium chloride, which helped the crystals grow more uniformly and reduced strain. Then they added two organic compounds—DMOAI and PEACl—to keep the ions in the material stable and in place.

“The solar cell with these tiny defects is like a cake cut into pieces,” explained lead author Siming Huang, a PhD student at UCL. “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.”

The treatments completely changed how the solar cell’s surface behaves. Tests showed that the surface switched from an n-type to a p-type structure, which made it much easier for electricity to flow through the material.

Indoor Solar Cells

The result is a perovskite cell tuned to a bandgap of 1.75 electron volts — just right for gobbling the higher-energy, mostly visible light indoors.

The team’s solar cells performed best under 1000 lux LED light, which corresponds to the brightness of a well-lit office. In those conditions, the device reached a power conversion efficiency (iPCE) of 37.6%, a record for perovskite cells designed for indoor use. After 100 days, the cells retained 92% of their initial performance; even after 300 hours of relentless bright light at 55°C, they clung to three-quarters of their efficiency.

To understand why this matters, consider the average smart home today. Every door sensor, remote control, and thermostat often relies on a small battery. Multiply that by billions of devices—and by how often those batteries are changed—and the environmental cost piles up.

“Billions of devices that require small amounts of energy rely on battery replacements—an unsustainable practice,” said Dr. Abdi-Jalebi. “This number will grow as the Internet of Things expands.”

What Happens Next?

Right now, the UCL solar cells exist only in the lab. But the researchers say they’re already in talks with industry partners.

“We are currently in discussions with industry partners to explore scale up strategies and commercial deployment,” said Dr. Abdi-Jalebi.

Because the perovskite cells can be printed using simple processes and rely on abundant elements, mass production may not be so far away. And if that happens, the impact could ripple far beyond convenience. These cells could help reduce battery waste, support smart cities, and power the next generation of autonomous IoT devices.

The findings appeared in the journal Advanced Functional Materials.