Boosting the Stability of Low-Cost, Large-Area Solar Modules

The study supports prior evidence that a commonly used material in PSCs, called titanium dioxide, degrades the devices and limits their lifetime.

(Left to right) Dr. Luis Ono, Dr. Zonghau Liu, Prof. Yabing Qi, Dr. Dae-Yong Son, Dr. Longbin Qiu, and Dr. Sisi He of the Energy Materials and Surface Sciences Unit. Credits: OISF

Scientists at the Okinawa Institute of Science and Technology Graduate University (OIST) have resolved a fundamental weakness in a promising solar technology known as Perovskite Solar Cells, or PSCs. According to their research results, their innovation can improve both the devices’ stability and scalability in one fell swoop and could be key to moving PSCs to market.

Third-generation solar cells efficiently convert sunlight into usable electricity and cost less energy to manufacture than old-school silicon cells. PSCs, in particular, has garnered the attention of science and industry thanks to their low cost and high efficiency. Though their performance is promising in lab tests, the devices still suffer from low stability and cannot be produced commercially until they’re built to last.

“We need solar modules that can last for at least 5 to 10 years. For now, the lifetime of PSCs is much shorter,” said Dr. Longbin Qiu, first author of the paper and a postdoctoral scholar in the OIST Energy Materials and Surface Sciences Unit, led by Prof. Yabing Qi.

The study, published online in Advanced Functional Materials supports prior evidence that a commonly used material in PSCs, called titanium dioxide, degrades the devices and limits their lifetime.

The researchers replaced this material with tin dioxide, a stronger conductor without these degrading properties. They optimised their method of applying tin dioxide to produce stable, efficient and scalable PSCs.

In experiments, the researchers found that tin dioxide-based devices showed lifetimes over three times longer than PSC devices using titanium dioxide. “Tin dioxide can give users the device performance they need,” said Qiu.

Their new solar cells achieved an efficiency of over 20 percent. To demonstrate the scalability of this new method, the researchers then fabricated 5 by 5-centimeter solar modules with a designated area of 22.8 square-centimeters, finding that the resulting devices showed over 12 percent efficiency.

The team plans to continue optimising their PSC design with the goal of producing large-scale solar modules with improved efficiency. The research unit experiments with flexible, transparent solar devices and aims to apply their optimised PSC design in solar windows, curtains, backpacks and deployable charging units.

“We want to scale these devices up to a large size, and though their efficiency is already reasonable, we want to push it further,” said Prof. Qi. “We are optimistic that in the next few years, this technology will be viable for commercialisation.”

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