Yang Yang Group Website: http://yylab.seas.ucla.edu/
UC Case Nos. 2015-556, 2018-019, 2022-209
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Modulating Heterointerface Energetics for Operationally Stable Perovskite Solar Cells (UCLA Case No. 2022-206)
Researchers at UCLA have developed a novel fabrication approach that stabilizes the surface of perovskite solar cells without hindering the efficiency of the solar energy conversion. By manipulating the surface energetics of the solar cells and applying a unique surface treatment, the long-term stability of perovskite-based solar cells was improved. In testing, devices treated with this method showed improved resistance to degradation, and electron microscope examination of the tested devices revealed significantly suppressed ion migration and heterointerface degradation, compared with conventional PSCs. This process is well suited to existing fabrication protocols which enables low manufacturing costs and decreases the barrier for widespread adoption.
Tan, S., Huang, T., Yavuz, I. et al. Stability-limiting heterointerfaces of perovskite photovoltaics. Nature 605, 268–273 (2022). https://doi.org/10.1038/s41586-022-04604-5
Efficient and Stable Perovskite Solar Cells with All Solution Processed Metal Oxide Transporting Layers (UCLA Case No. 2015-556)
This invention presents a unique perovskite solar cell that uses metal oxide films for the charge transport layer. Metal oxides offer the advantage of higher carrier mobility and superior stability than typical organic materials and they can be processed easily via solution. This unique lead halide perovskite solar cell has achieved a ~16% efficiency and improved stability of 60 days under normal operating conditions.
US Patent Application 15/553,483
Biography:
Yang Yang is the Carol and Lawrence E. Tannas Jr. Chair in Engineering and a Professor of Materials Science and Engineering at the UCLA Henry Samueli School of Engineering and Applied Science. His notable contributions to the field of perovskite photovoltaics include tandem solar cells, planar device architectures, and LED devices. Moreover, his work has resulted in perovskite tandem devices with record-breaking efficiencies. In addition to record-breaking perovskite solar cells, his group also develops record-breaking organic photovoltaics.
Professor Yang has been cited by Thomson Reuters IP and Science as one of the “World’s Most Influential Scientific Minds” and one of the world’s most highly cited researchers in chemistry and materials science. He is a fellow of the American Physical Society, the Materials Research Society, and the Royal Society of Chemistry. Yang, who joined the UCLA faculty in 1997, has more than 60 patents and has published more than 290 peer-reviewed papers. He received his Ph.D. in physics and applied physics from the University of Massachusetts Lowell.
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Background:
Organic-inorganic hybrid materials, particularly perovskites, represent a new class of materials that may combine desirable properties of both organic and inorganic materials in photovoltaic applications. Organic materials have low manufacturing costs while inorganic materials typically produce higher performing devices, but require expensive, complicated manufacturing. Perovskite hybrid materials have been proven to combine the high performance of inorganic materials with the flexibility of organic materials. However, the highest performing perovskite-based devices typically are fabricated using costly vacuum deposition techniques and high temperatures. Solution processing methods, along with improvements in performance, would allow the perovskite-based electronic devices to be competitive alternatives to traditional silicon and other inorganic technologies.
Lead halide perovskite solar cells offer excellent photovoltaic efficiencies (up to 15%), but both the perovskite material and the charge transport layers have poor stability, where the device degrades within days under normal conditions. Specifically, organic charge transport layers are important for energy level matching and charge transport, but their use is limited because they have poor device stability and are costly to fabricate. The use of inorganic materials to replace the organic transport layers offers a promising avenue to circumvent the disadvantages of these layers for solar cell applications.
Over the last decade, the certified power conversion efficiency (PCE) of perovskite solar cells has increased to 23.1%, establishing perovskites as viable alternatives to the widely used silicon solar cell. Further PCE improvement can be achieved by reducing the microscale heterogeneity of the films, but conventional techniques to improve crystal growth are time consuming. Therefore, novel scalable and efficient strategies that improve microscale properties will be important to further enhance the photovoltaic properties of perovskite solar cells. Another technique for PCE improvement is adopting a tandem architecture, which uses multi-junction solar cells to harness a broader range of the solar spectrum. While this design is typically implemented in III-V semiconductors to achieve ~30% efficiencies, their high fabrication costs hinder mass commercialization. Therefore, applying tandem architectures to solution-processed perovskite solar cells could provide a pathway for improved PCEs at commercially viable costs.
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Applications:
- Grid solar cells
- Portable solar cells
- LEDs
- Field-effect transistors
- Wearable electronics
Advantages:
- High performance electronic devices, including solar cells with up to ~23% efficiency
- Solution processable – low-cost and versatile manufacturing
- Uses inexpensive, well-studied materials for many layers
- May use a variety of substrates, including flexible plastics
- Enhanced and controlled reconstruction between organic and inorganic components during film formation leading to superior device performance
- Continuous, compact, large grain size, full surface coverage of PVSK thin films
- Technique applicable to a range of substrates and devices including flexible films, multi-junction solar cells, LEDs, sensors and superconductors