Scientists have long believed that perovskite solar cells could transform the solar industry because they are light, inexpensive and highly efficient.
However, one major weakness has held them back: they rely on indium tin oxide, or ITO, a fragile and costly material that cracks easily and limits how flexible a solar panel can be.
A new study led by the University of Surrey suggests that replacing ITO with single-walled carbon nanotubes could finally unlock the full potential of flexible, durable and affordable solar technology.
Carbon nanotubes are tiny, tube-shaped structures made of carbon atoms. They are extremely strong, excellent at conducting electricity and can be made transparent enough to let sunlight reach the active solar materials underneath.
In this new research, scientists discovered that treating these nanotube films with sulfuric acid dramatically improves their electrical performance while keeping them clear.
The treatment creates a special nickel-based layer that enhances the connections within the solar cell, making the whole device work more efficiently.
The results surprised even the research team.
Their flexible perovskite solar cells achieved more than 20 percent efficiency across large surfaces, and smaller devices reached a record efficiency of 24.5 percent—performance levels that are competitive with some of the best solar technologies available today.
These gains were achieved without using any ITO at all.
Another major advantage of carbon nanotubes is how easy they are to scale up. The films can be produced using roll-to-roll chemical vapor deposition, a manufacturing method already used for large electronic components.
This means the technology could realistically be produced in factories and used in real-world products, rather than being stuck in the laboratory stage.
The new design also proved far more stable than traditional ITO-based perovskite cells. After being exposed to heat, humidity and sunlight for a month, the nanotube-based devices kept more than 95 percent of their original performance.
That level of durability is a huge improvement for perovskite technology, which often struggles with degradation over time.
Flexibility tests told a similar story. While ITO-based devices lost nearly 75 percent of their efficiency after being bent 1,000 times, the nanotube version lost only about 5 percent and showed no cracks or peeling. This toughness could make it possible to create solar panels that curve around roofs, wrap around portable electronics or integrate into clothing and building materials.
The researchers also highlight the environmental and financial benefits. Producing carbon nanotube films can be around six times cheaper than making ITO coatings, reducing manufacturing costs by roughly $200 per square meter. Since indium is rare and energy-intensive to mine, switching to carbon-based materials could make solar production greener and more sustainable.
Perovskite solar cells have always been promising, but their fragile components have slowed down commercial use.
By replacing ITO with carbon nanotubes, this study clears a major obstacle and brings the world closer to flexible, lightweight solar panels that could power everything from everyday gadgets to future smart buildings.
