The race for higher efficiencies in solar cells has captured the imagination of researchers, investors and the general public alike. Record-breaking efficiencies promise more energy from smaller and cheaper solar panels. In only 15 years, perovskite solar cells achieved high efficiencies over 25% — it took 37 years to achieve comparable efficiencies with popular crystalline silicon solar cells. Meanwhile, tandem cells are easily breaking the 30% efficiency barrier with perovskite-silicon structures reaching 33.9% in 2023.

However, there is another critical aspect of solar technology: stability. While efficiency is an important factor, stability ultimately determines its real-world impact. For emerging technologies like perovskites and organic photovoltaics, the challenge of maintaining performance over time in real-world conditions is a far greater barrier to adoption than achieving peak efficiency in a lab.

The problem with stability in emerging technologies

Emerging solar technologies, while promising, are less stable than traditional silicon-based systems. This instability is rooted in the properties of the materials themselves and their susceptibility to environmental factors.

• Perovskite solar cells are known for their high efficiencies and low production costs, but they degrade quickly when exposed to heat, humidity and UV light. These factors are inevitable in outdoor environments.
• Organic photovoltaics (OPVs) are flexible, lightweight solar cells that face challenges with moisture and oxygen ingress, leading to performance drops over time.
• Cadmium telluride thin-films are more durable than some next-gen materials but can still suffer from defects introduced during manufacturing. These defects can compromise long-term stability.

The primary issue is that while these materials perform exceptionally well over a short period in controlled laboratory settings such as a glove box, their behavior under real-world conditions often falls short. Factors like temperature fluctuations, pollution, mechanical stress and exposure to elements can accelerate degradation, reducing the effective lifespan of these solar cells.

Why stability matters more than efficiency

High-efficiency solar cells generate excitement and investment but, without stability, their potential impact is limited. Solar panels that degrade quickly will produce significantly less energy over their lifetime, regardless of the high efficiencies achieved in the lab. When introducing new technologies, if they fail to demonstrate reliability, they will struggle to gain trust from investors, regulators and consumers. Stability is a key factor in building credibility for new materials and designs.

Solar panels are a long-term investment for both residential and commercial installations. Frequent replacements or repairs due to instability increase the overall cost of ownership, making solar less attractive to consumers and businesses. Instability also impacts large-scale solar farms, where replacing many solar panels becomes a logistical and financial challenge.

Panels with short lifespans also contribute to the growing issue of solar waste. As installations scale globally, ensuring durability can help minimize the environmental footprint of solar technology. In this sense, stability aligns with the sustainability ethos of renewable energy by reducing resource consumption over time. Plus, the degradation of some new solar materials can be dangerous. Perovskite solar cells contain lead-halide complexes that dissolve in water. Without proper encapsulation there are risks of these poisoning the local environment.

Reframing industry priorities

The solar industry’s obsession with efficiency is understandable. Efficiency metrics are easy to communicate, resonate with consumers and drive scientific notability. However, for solar energy to become a truly transformative force in the global energy landscape, durability must take center stage.

• Shift research focus: Academic and industry researchers should allocate more resources to studying degradation mechanisms and developing durable materials.
• Incentivize stability: Governments and funding agencies can encourage stability research by tying incentives to long-term performance metrics rather than peak efficiency alone.
• Educate stakeholders: Manufacturers and installers should emphasize stability to consumers, highlighting the long-term benefits of durable solar technologies.
• Industry collaboration: Researchers, policymakers and manufacturers must work together to establish robust standards and share data on durability testing.

Efficiency captures attention, but stability ensures impact. For next-generation solar cells to achieve widespread adoption, they must prove their ability to perform consistently over decades in real-world conditions. By prioritizing stability in research, manufacturing and policy, the solar industry can create technologies that are not only high-performing but also reliable and sustainable. This shift in focus will lay the foundation for a more resilient and impactful renewable energy future, ensuring solar remains at the forefront of the global energy transition.

Innovations tackling stability challenges

The good news is that researchers and industry leaders are already actively addressing the stability issues in next-gen solar cells with progress being made in several key areas.

Material engineering

Advances in protective coatings and encapsulation technologies are shielding sensitive materials like perovskites and OPVs from environmental stressors. These barriers prevent moisture, oxygen and UV light from reaching the active layers of the cells. Additionally, a significant proportion of perovskite and organic photovoltaic research is dedicated to finding more stable materials, and results struggle to be published without some comment on device stability.

Researchers are also exploring lead-free perovskites and other non-toxic materials that maintain performance while improving environmental safety and stability.

Manufacturing innovation

Defects are the gateway to degradation in many thin-film solar cells. Improvements in manufacturing processes can reduce the number of defects in a film and improve device stability. Perfecting deposition techniques minimizes stress on materials to extend their lifespans. Optimizing your deposition technique to control film formation and drying mechanics can have a stark effect on device stability.

Device engineering

The interfaces between layers in a device can become a hotspot for unwanted reactions and ion migration. In solar cells, the layers are often very thin to allow efficient charge movement and light transmission. This means they will also allow movement of materials out of the device, or contaminants into the device. To address this challenge in multi-layered devices like perovskite solar cells, barrier or interfacial layers can be incorporated to prevent undesired migration and enhance device stability.

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Mary is a content writer and application scientist at Ossila Ltd. In this role, she creates and reviews informative articles to help users get the most out of our equipment and materials, and to make cutting edge scientific research and know-how as accessible as possible. Before this, she completed a PhD specializing in the scalability of perovskite solar cells. During this time, she co-authored several research papers and conference presentations on perovskite and organic photovoltaic research, acting as lead investigator in several key projects. She has a MPhys degree from the University of Sheffield.