Scientists make perovskite solar cells perform in high temperatures

Compared to conventional silicon solar cells, perovskite solar cells can be produced utilizing less complicated and expensive technologies by using solution processing methods like spin coating and inkjet printing.

Despite their potential, perovskite solar cells face some challenges. They are sensitive to moisture, can degrade over time, and exhibit thermal instability, not functioning well in high temperatures. Researchers are working to improve their stability and durability and may have just come up with a solution to deal with the last issue.

A special kind of self-assembled monolayer

A special kind of self-assembled monolayer, or SAM for short, has been created by a team at CityU and anchored on a nickel oxide surface as a charge extraction layer. This has the potential to effectively tackle thermal instability.

 “Our approach has dramatically enhanced the thermal robustness of the cells,” said Professor Zhu Zonglong of the Department of Chemistry at CityU.

“By introducing a thermally robust charge extraction layer, our improved cells retain over 90% of their efficiency, boasting an impressive efficiency rate of 25.6%, even after operated under high temperatures, around (65℃) for over 1,000 hours. This is a milestone achievement.”

Zhu compared perovskite solar cells to a sports vehicle that performs remarkably well in mild weather but tends to overheat and function poorly on a hot day, despite having a high power conversion efficiency. This was an important barrier to the cells’ broad adoption.

Transforming the solar energy landscape

The CityU team has now laid the groundwork for perovskite solar cells to function well even in high-temperature environments by increasing the thermal stability of these cells using the newly-introduced SAM. The development could completely transform the solar energy landscape.

“This breakthrough is pivotal as it addresses a major obstacle that previously impeded wider adoption of perovskite solar cells. Our findings could significantly broaden the utilization of these cells, pushing their application boundaries to environments and climates where high temperatures were a deterrent,” said Professor Zhu. 

Perovskite solar cells have a tremendous potential to revolutionize the solar energy sector. Their use into widely established solar technology may drastically lower the price of producing renewable energy making the clean energy more accessible worldwide. As such, once completely developed and commercialized, this new technology might significantly reduce our reliance on fossil fuels and help tackle the global climate catastrophe by making solar power mainstream.

The study is published in the journal Science.

Study abstract:

P-i-n geometry perovskite solar cells (PSCs) offer simplified fabrication, greater amenability to charge extraction layers, and low-temperature processing over n-i-p counterparts. Self-assembled monolayers (SAMs) can enhance the performance of p-i-n PSCs but ultrathin SAMs can be thermally unstable. We report a thermally robust hole-selective layer comprised of nickel oxide (NiOx) nanoparticle film with a surface-anchored (4-(3,11-dimethoxy-7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid (MeO-4PADBC) SAM that can improve and stabilize the NiOx/perovskite interface. The energetic alignment and favorable contact and binding between NiOx/MeO-4PADBC and perovskite reduced the voltage deficit of PSCs with various perovskite compositions and led to strong interface toughening effects under thermal stress. The resulting 1.53–electron-volt devices achieved 25.6% certified power conversion efficiency and maintained >90% of their initial efficiency after continuously operating at 65 degrees Celsius for 1200 hours under 1-sun illumination.