Most perovksite solar cells or LEDs use polycrystalline thin films that can be printed for flexible panels but these have fundamental llimits to the eficiency of the energy conversion and issues with lifetime that researchers around the world are looking to overcome.
The fabrication method developed by Professor Sheng Xu at the Jacobs School of Engineering nanoengineering lab uses standard semiconductor fabrication processes. This results in flexible single-crystal perovskite films with controlled area, thickness, and composition. These single-crystal films showed fewer defects, greater efficiency and enhanced stability than their polycrystalline counterparts, which could lead to the use of perovskites in solar cells, LEDs, and photodetectors.
The findings were published findings in Nature.
"Our goal was to overcome the challenges in realizing single-crystal perovskite devices," said Yusheng Lei, a nanoengineering graduate student and first author of the paper. "Our method is the first that can precisely control the growth and fabrication of single-crystal devices with high efficiency. The method doesn't require fancy equipment or techniques. The whole process is based on traditional semiconductor fabrication, further indicating its compatibility with existing industrial procedures."
"Currently, almost all perovskite fabrication approaches are focused on polycrystalline structures since they're easier to produce, though their properties and stability are less outstanding than single-crystal structures," said Yimu Chen, a nanoengineering graduate student and co-first author of the paper.
Controlling the form and composition of single-crystal perovskites during fabrication has been difficult. "Modern electronics such as your cell phone, computers, and satellites are based on single-crystal thin films of materials such as silicon, gallium nitride, and gallium arsenide," said Xu. "Single crystals have less defects, and therefore better electronic transport performance, than polycrystals. These materials have to be in thin films for integration with other components of the device, and that integration process should be scalable, low cost, and ideally compatible with the existing industrial standards. That had been a challenge with perovskites."
The team is the first to successfully integrate perovskites into the industrial standard