Protective coating significantly extends perovskite solar cell life

Northwestern College scientists have developed a brand new protecting coating that considerably extends the lifetime of perovskite photo voltaic cells, making them extra sensible for purposes outdoors the lab.

Though perovskite solar cells are extra environment friendly and cheaper than conventional silicon photo voltaic cells, perovskite has—till now—been restricted by its lack of long-term stability. Sometimes, perovskite photo voltaic cells use an ammonium-based coating layer to reinforce effectivity. Whereas efficient, ammonium-based layers degrade below environmental stress, equivalent to warmth and moisture.

Northwestern researchers have now developed a extra sturdy layer—based mostly on amidinium.

In experiments, the brand new coating was 10 instances extra immune to decomposition in comparison with standard ammonium-based coatings. Even higher, the amidinium-coated cells additionally tripled the cell’s T₉₀ lifetime—the time it takes for a cell’s effectivity to drop 90% of its preliminary worth when uncovered to harsh conditions.

The analysis is published within the journal Science.

“The field has been working on the stability of perovskite solar cells for a long time,” stated Northwestern’s Bin Chen, who co-led the examine. “So far, most reports focus on improving the stability of the perovskite material itself, overlooking the protective layers. By improving the protective layer, we were able to enhance the solar cells’ overall performance.”

“This work addresses one of the critical barriers to widespread adoption of perovskite solar cells—stability under real-world conditions,” stated Northwestern’s Mercouri Kanatzidis, who co-led the examine. “By chemically reinforcing the protective layers, we’ve significantly advanced the durability of these cells without compromising their exceptional efficiency, bringing us closer to a practical, low-cost alternative to silicon-based photovoltaics.”

Chen is a analysis affiliate professor of chemistry at Northwestern’s Weinberg Faculty of Arts and Sciences. He co-led the examine with Ted Sargent, the Lynn Hopton Davis and Greg Davis Professor of Chemistry at Weinberg and professor {of electrical} and laptop engineering on the McCormick College of Engineering, and Kanatzidis, the Charles E. and Emma H. Morrison Professor of Chemistry at Weinberg. Yi Yang, a postdoctoral fellow co-advised by Sargent and Kanatzidis, is the paper’s first writer.

Perovskite as a substitute for silicon

In use for many years, silicon has been essentially the most generally used materials for the light-absorbing layer in photo voltaic cells. Whereas silicon is sturdy and dependable, it is costly to supply and is approaching its ceiling of effectivity. Searching for a decrease price and better effectivity photo voltaic cell, researchers just lately started exploring perovskites, a household of crystalline compounds.

Though it demonstrates promise as an economical different to silicon, perovskite has a comparatively quick lifespan. Extended publicity to daylight, excessive temperature fluctuations, moisture and humidity all trigger perovskite photo voltaic cells to degrade over time.

To beat this problem, the researchers added amidinium ligands, secure molecules that may work together with perovskite to offer long-lasting defect passivation and protecting results. Ammonium-based molecules have a nitrogen atom surrounded by three hydrogen atoms and one carbon-containing group, whereas amidinium-based molecules comprise a central carbon atom bonded to 2 amino teams. As a result of their construction permits electrons to unfold out evenly, amidinium molecules are extra resilient below harsh situations.

“State-of-the-art perovskite solar cells typically have ammonium ligands as a passivation layer,” Yang stated. “But ammonium tends to break down under thermal stress. We did some chemistry to convert the unstable ammonium into a more stable amidinium.”

The researchers carried out this conversion via a course of often known as amidination, wherein the ammonium group is changed with a extra secure amidinium group. This innovation prevented the perovskite cells from breaking down over time—particularly when uncovered to excessive warmth.

Document-breaking outcomes

The ensuing photo voltaic cell achieved a powerful 26.3% effectivity, which suggests it efficiently transformed 26.3% of absorbed daylight into electrical energy. The coated photo voltaic cell additionally retained 90% of its preliminary effectivity after 1,100 hours of testing below harsh situations, demonstrating a T₉₀ lifetime thrice longer than earlier than when uncovered to warmth and light-weight.

These experiments mark the most recent instance of improved perovskite photo voltaic cell efficiency from the Sargent lab. In 2022, Sargent’s group developed a perovskite photo voltaic cell that broke records for power effectivity and voltage. In 2023, his group launched a perovskite photo voltaic cell with an inverted structurewhich additionally improved its power effectivity. And earlier this 12 months, Sargent’s group incorporated liquid crystals to reduce the defects in perovskite movies, resulting in enhanced machine efficiency.

“Perovskite-based solar cells have the potential to contribute to the decarbonization of the electricity supply once we finalize their design, achieve the union of performance and durability, and scale the devices,” stated Sargent, who directs the Paula M. Trienens Institute for Sustainability and Vitality. “The primary barrier to the commercialization of perovskite solar cells is their long-term stability. But due to its multi-decade head start, silicon still has an advantage in some areas, including stability. We are working to close that gap.”

This analysis is straight tied to the Generate pillar—one of many Trienens Institute Six Pillars of Decarbonization. As part of the Generate pillar, Northwestern commits to constructing a brand new class of photo voltaic power manufacturing by specializing in high-efficiency multi-junction photo voltaic cells and next-generation photo voltaic cell supplies. Kanatzidis is a school co-chair of the pillar, and Chen is the implementation lead.