Scientists create high-efficiency solar cells that work best indoors and low-light spaces

Perovskite solar cells, often called PeSCs, are changing the way energy is captured—especially indoors. Unlike the rigid and heavy silicon panels fixed to rooftops, these thin and flexible materials can power small electronics under common lighting. What once seemed like a futuristic dream is now becoming a practical solution thanks to new ways of making these cells work better in low-light spaces.

Rethinking Solar Power for Indoor Light

You’ve probably seen solar panels soaking up sunlight outside. But researchers at National Yang Ming Chiao Tung University in Taiwan are shifting the focus indoors. Their latest innovation, published in APL Energy, shows that PeSCs can convert light from sources like overhead fluorescent bulbs into electrical power.

These solar cells aren’t built the same way as traditional silicon-based ones. Instead, PeSCs use a crystal-like structure called perovskite. This material allows the devices to be thin, bendable, and even see-through. That opens the door for them to be used on surfaces beyond rooftops—like on windows, wearables, and even the back of remote controls.

“The most common solar cells in the market are silicon-based,” explained researcher Fang-Chung Chen. “However, PeSCs can be made thin, lightweight, flexible, and even semi-transparent, whereas silicon panels are rigid and heavy, which limits their use to flat, durable surfaces.” But working indoors means the cells need to gather power from dimmer light. That’s where bandgaps come in.

Tuning the Light Absorption Sweet Spot

The bandgap of a solar cell controls which wavelengths of light the material can absorb. Silicon’s bandgap is fixed, which limits how much it can adapt to different lighting conditions. PeSCs are more tunable, and that gives scientists an advantage when designing cells that work under office lights instead of direct sun.

To create this tailored energy absorption, the researchers adjusted the chemical makeup of the perovskite. They altered the ratio of halide ions in the mix to form a wide-bandgap material. This version absorbs indoor lighting more efficiently.

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Still, there’s a catch. “Tuning the bandgap, unfortunately, accompanies a negative effect: It brings defects in the perovskite layers,” said Chen. These defects interfere with the flow of electricity and reduce performance. So the team had to find a fix. That’s where their second breakthrough comes in—passivation using special molecules that seal the defects and boost performance.

Healing Defects for a Stronger Solar Cell

To solve the problem of material defects, the team added chelating agents containing phosphorus–oxygen (P=O) bonds during the cell-making process. These molecules attach themselves to the surface of the perovskite and “passivate” it, which means they reduce the number of defects and block harmful reactions.

The process was simple: the researchers mixed these agents into the anti-solvent used during the fabrication of the solar cells. This step improved both the efficiency and durability of the devices.

Among the agents tested, one in particular—2,8-bis(diphenyl-phosphoryl)-dibenzo[b,d]furan, or PPF—stood out. PPF provided better charge transport and deeper passivation than the other materials. By using PPF, the researchers achieved a power conversion efficiency (PCE) of 12.76% under bright outdoor-like conditions (12,000 lux). While that’s lower than the best silicon cells, which can reach about 26%, it’s still impressive for a flexible, indoor-focused technology.

More remarkable was the cell’s indoor performance. Under 2,000 lux—similar to a typical office environment—the PPF-treated PeSCs reached a PCE of 38.70%. That means they were able to convert nearly 39% of the light energy into usable electricity under low-light conditions.

Stable, Flexible, and Ready for Real Life

The researchers originally hoped to boost energy output, but they got something extra. Their method also made the PeSCs more stable over time. “In the beginning, we only expected our approach could improve the device efficiency,” said Chen. “Because the poor reliability of PeSCs is a large challenge for their adoption, we hope our proposed method can pave the way toward the commercialization of perovskite solar panels.”

This added stability solves one of the biggest problems for perovskite cells. Unlike silicon, perovskite can degrade quickly due to moisture, heat, or other environmental factors. By sealing defects, the team’s passivation strategy protects the cell from damage and corrosion, extending its usable life.

That brings the cells one step closer to being used in everyday devices, especially those that don’t need much power. Remote controls, motion sensors, wearables, and small Internet of Things (IoT) devices could all benefit. And because the materials are cheap and the process is simpler than making silicon wafers, there’s potential for large-scale, affordable manufacturing.

Bright Future Under Dim Light

As more technology shifts indoors, the need for low-light power solutions grows. Devices that once ran on disposable batteries could soon recharge themselves under ordinary lights.

Thanks to flexible perovskite solar cells, energy doesn’t have to come only from the sun anymore. With the ability to harvest light in offices, homes, and factories, these cells offer a powerful new way to power the future—one photon at a time.

Note: The article above provided above by The Brighter Side of News.

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