Perovskite solar cells have dazzled researchers for more than a decade. Cheap to make and capable of converting sunlight with record-breaking efficiency, they’re hailed as the next big leap beyond silicon. But stability has always been a catch. Under heat and stress, perovskites tend to break down, limiting their practical use on rooftops or in solar farms.
But research from Ulsan National Institute of Science and Technology (UNIST) in South Korea [35.6°N, 129.3°E] has made a decisive advance by replacing one unstable component with a tougher alternative. The result: perovskite devices that are not only highly efficient but also able to withstand punishing conditions.
The Problem with Volatile Additives
To achieve high performance, today’s perovskite solar cells use a liquid additive; 4-tert-butylpyridine or tBP. It plays an important role in stabilising lithium ions inside the device, but it comes with serious drawbacks. The additive is volatile, meaning it can evaporate, and corrosive, meaning it can attack the delicate layers inside the cell. Over time, this leads to defects — pinholes, byproducts, and weakened performance, especially under heat.
In other words, the very chemical that makes the cells efficient also undermines their longevity.
The Solid-State Solution
The research team introduced a new additive; 4-(N-carbazolyl)pyridine, or 4CP. Unlike its liquid predecessor, 4CP is solid and non-volatile, so it doesn’t evaporate or corrode. Crucially, it still performs the same stabilising role, keeping lithium ions in balance and enabling the chemical reactions that make the device run smoothly.
The impact was dramatic:
- Efficiency: 26.2% (25.8% independently certified), on par with the best perovskites.
- Long-term stability: 3,000 hours of continuous operation while maintaining 80% of their initial performance.
- Extreme durability: 200 thermal shock cycles between –80 °C and +80 °C (conditions similar to those faced by satellites in orbit) with almost no loss of efficiency.
- Consistent output: 65–85 °C, temperatures typical of hot summer days or rooftop installations.
Why This Matters
For solar installers, policymakers, and everyday energy users, this research points to a world where perovskite panels could finally move from the lab to the field. By removing one of the biggest sources of instability, the study makes perovskites more realistic for commercial deployment.
And the benefits could be profound: lighter, cheaper panels that capture more of the sun’s energy, deployed alongside silicon to create tandem devices capable of surpassing 30% efficiency.
The Takeaway
The clean energy transition depends not only on breakthrough efficiency but also on reliability. This work shows how a single chemical swap — from a volatile liquid to a stable solid — can shift perovskite solar cells from fragile experiments toward practical, long-lasting technology. It’s a reminder that sometimes the biggest advances come from the smallest changes at the molecular level.
Source
Non-volatile solid-state 4-(N-carbazolyl)pyridine additive for perovskite solar cells with improved thermal and operational stability, Nature Energy, 2025-08-04
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