Efficient and stable solar cells can now be mass produced

Scientists from the City University of Hong Kong (CityUHK) have developed highly efficient, printable and stable perovskite solar cells, to help achieve carbon neutrality. The new type of perovskite solar cells can be mass produced at a speed comparable to newspaper printing, with a daily output of up to 1000 solar panels. Due to their flexible, semi-transparent characteristics, the perovskite solar cells can also be made into light-absorbing glass windows.

Led by Professor Alex Jen Kwan-yue, professor of materials science, the researchers demonstrated an effective strategy to enhance the long-term stability of perovskite-organic tandem solar cells. The integrated cells retain over 90% of their initial power conversion efficiency (PCE) after 500 hours of operation.

The operational stability of wide-bandgap perovskites has been a challenge for scientists; the CityUHK team addressed the issue with novel material science solutions by designing a series of organic redox mediators with appropriate chemical potentials to selectively reduce iodine and oxidise metals. After the perovskite device was integrated into the monolithic perovskite-organic tandem solar cell as a wide-bandgap subcell, the encapsulated tandem cell was subjected to 1-sun illumination (AM 1.5G spectrum, without a UV filter). It retained 92% of its initial PCE after 500 hours of continuous operation at ~45°C. The researchers also reported high efficiency of 25.22% (certified 24.27%). The device also exhibited good operational stability in humid air (relative humidity, 70–80%).

“We were the first team to propose the use of redox and chemical synthesis methods to fundamentally solve the problem, effectively ensuring the stability of perovskite solar cells,” said Dr Wu Shengfan, a key member of the research team.

The research results, published in the journal Nature Energy, will be transformed into practical applications through the start-up company HKTech Solar that will be managed by Dr Francis Lin, a postdoctoral student of Professor Jen.

Perovskite photovoltaics can absorb energy even under weak indoor light and have mechanical flexibility. They can be integrated and applied in different scenarios, from large buildings and farms to various components of the Internet of Things. The researchers also plan to set up a pilot production line with an annual output of 25 megawatts in Hong Kong within a year and a half and launch products for industry matching investors to test applications.

Image credit: iStock.com/BorisRabtsevich