Solar energy has long been hailed as a promising source of renewable energy. However, traditional silicon solar cells are expensive and unsustainable to produce. Fortunately, next-generation solar materials, such as perovskite solar cells, offer a cheaper and more sustainable alternative. Perovskite solar cells have a unique crystalline structure that excels at absorbing visible light. Despite their potential, perovskite solar cells face durability challenges. In a recent breakthrough, an international team of scientists, led by Penn State faculty Nelson Dzade, developed a new technique to create more durable perovskite solar cells without compromising efficiency. This article explores the innovative method and its implications for the future of solar energy.
Perovskite solar cells have gained attention for their ability to be manufactured at room temperature using less energy compared to traditional silicon materials. This makes them cost-effective and environmentally friendly. According to Dzade, assistant professor of energy and mineral engineering, the leading candidates for perovskite solar cells, hybrid organic-inorganic metal halides, have organic components that are vulnerable to moisture, oxygen, and heat. Exposure to real-world conditions can lead to rapid performance degradation. To overcome this challenge, the scientists turned to all-inorganic perovskite materials, specifically cesium lead iodide, known for its superior tolerance to environmental factors.
While all-inorganic perovskite materials offer better stability, they face a different obstacle: polymorphism. Cesium lead iodide has multiple phases with different crystalline structures. Two of these phases are photoactive and suitable for solar cells. However, they can easily convert to an undesirable non-photoactive phase at room temperature, degrading the efficiency of the solar cell. To address this issue, the researchers combined the two photoactive polymorphs to form a phase-heterojunction. This unique structure suppresses the transformation to the undesirable phase, resulting in improved material stability and enhanced power conversion efficiency.
The scientists fabricated a device using the dual deposition technique, developed by Dzade’s colleagues at Chonnam University in South Korea. This technique involves depositing one phase with a hot-air technique and the other with triple-source thermal evaporation. The researchers found that adding small amounts of molecular and organic additives during the deposition process improved the electrical properties, efficiency, and stability of the device. The device achieved a remarkable 21.59% power conversion efficiency, one of the highest reported for this approach. Additionally, the devices maintained over 90% of the initial efficiency after 200 hours of storage under ambient conditions.
Dzade modeled the atomic-scale structure and electronic properties of the heterojunction. The results highlighted the stability and coherent interface structure created by bringing the two photoactive phases together. This structure promotes efficient charge separation and transfer, crucial for achieving high-efficiency solar devices. The dual deposition technique not only has implications for perovskite solar cells but also for other halide perovskite compositions. By extending the technique to different compositions, researchers can further enhance the efficiency and stability of solar cells based on all inorganic perovskites.
In addition to improving efficiency, the researchers aim to make phase-heterojunction cells more durable for real-world conditions. Scaling the size of perovskite solar cells to match traditional solar panels is another important step in their development. With the breakthrough achieved in this study, the researchers believe it is possible to surpass an efficiency of 25% in the near future. This significant advancement could revolutionize the solar energy industry and bring us closer to a sustainable future.
The development of more durable perovskite solar cells is a significant milestone in harnessing the potential of solar energy. Through the innovative use of phase-heterojunctions and the dual deposition technique, scientists have overcome the challenges of polymorphism and improved the stability and efficiency of perovskite solar cells. As this technology continues to evolve, it offers a promising solution for affordable and sustainable solar energy production. With further advancements and scaling efforts, perovskite solar cells may soon become the dominant player in the renewable energy landscape, paving the way for a cleaner and greener future.