Molecular coating unites photovoltaics, photodetection in one device
A team of researchers from Korea University and Dongguk University has created a new molecular coating for organic solar cells. According to the team, this innovation now enables a single device to act as both a solar cell and a photodetector, without the usual trade-offs.
The breakthrough also resolves the major conflict between the two technologies, namely that solar cells are designed to rapidly move charge for maximum power generation, while photodetectors are designed to suppress charge movement so they can detect faint light signals.
Since they conflict, researchers typically keep them as separate devices; however, this is no longer the case, thanks to this new breakthrough. This was achieved by using a new coating made of a single, simple molecule of benzene and phosphonic acid, or BPA for short.
When applied to a common transparent electrode (indium tin oxide, or ITO), BPA forms a self-assembled monolayer (just one molecule thick) that chemically bonds to the surface.
This setup enables the energy alignment at the interface so the device can extract charges efficiently, making it good for solar cell operation. It allows it to suppress background noise, which is good for light detection.
Solar-cell-come-photodetector
This is significant because current indoor solar-powered electronics, such as smart sensors, wearables, and Internet-of-Things (IoT) devices, require power to operate. Batteries wear out, and hardwiring them isn’t always possible.
Indoor light is abundant, but normal solar cells aren’t optimized for it. Until now, you have needed two separate devices: one for harvesting light and one for detecting it, which doubles the cost and space requirements.
The new BPA photodetector-solar cell now allows for dual function on one film, enabling it to generate power and detect light simultaneously. The BPA film works under typical indoor lighting (1,000 lux LED at 2700K).
When tested, the researchers found that it achieved 28.6% efficiency indoors, which is better than conventional coatings. It also remained stable, showing 87% performance after 1,000 hours of indoor light.
The new technology should also be able to scale well to larger sizes without losing much efficiency. It is also very cheap, having nearly 9× better cost-to-performance ratio than existing materials.
Looking at the bigger picture, the new film enables self-powered indoor devices that require no batteries and no recharging. It could prove useful for wearables, smart building sensors, industrial monitors, and even tiny surveillance systems.
Detects light and generates power
It should also be compatible with flexible electronics (bendable/wearable systems). The BPA film could also be a path to cheaper, more sustainable IoT ecosystems.
The research is not only interesting, but it is also a classic case of how a small change can have a big impact. In this case, just adding one molecule at the interface solved a problem that’s been blocking dual-function indoor devices for years.
To this end, instead of complexity, the team showed that deliberate simplification (a minimalist molecule) is the key. This could accelerate mass adoption of indoor photovoltaics, cutting both cost and material use, while powering the billions of smart devices expected in homes, factories, and healthcare.
This breakthrough could power a new generation of battery-free sensors and wearables, making indoor electronics cheaper, more efficient, and more sustainable.