Solving the Colloidal and Photophysical Instability Problems of Perovskite Quantum Dots via Surface Ligand Engineering

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With support from the Macromolecular, Supramolecular and Nanochemistry (MSN) Program in the Division of Chemistry and the Solid State and Materials Chemistry (SSMC) Program in the Division of Materials Research, Professors Mattoussi and Ma at Florida State University are developing strategies to enhance the long-term stability of colloidal perovskite nanocrystals. Colloidal perovskite nanocrystals are a class of semiconductor nanocrystals that exhibit several unique physical and spectroscopic properties. These properties can be extremely useful for various technological applications, such as energy harvesting and light-emitting devices (LEDs). However, their limited colloidal and structural stabilities have prevented in depth understanding and inhibited further integration of these materials into electronic devices. The strategies explored by Professors Mattoussi and Ma involve the design of a new set of metal-coordinating polymers that may impart long-term stability to these materials over a wide range of conditions, preserve the nanocrystal integrity, and enhance their optical and electronic properties, thereby bringing the materials closer to use in industrial applications. The research provides an example where chemistry, materials science,and engineering are combined to address important fundamental problems and to advance new technologies. The project also provides a good training for graduate and undergraduate students in aspects ranging from chemical synthesis, engineering, and advanced analytical characterization of light-emitting devices. In addition, Professors Mattoussi and Ma are collaborating with the Florida Center for Research in Science, Technology, Engineering, and Mathematics (FCR-STEM) to create and disseminate K-12 science videos to teachers and students.This NSF-supported project addresses some of the salient problems affecting perovskite nanocrystals, such as poor colloidal and structural stability, using interfacial chemistry approaches. Colloidal perovskite nanocrystals have cores made of either all–inorganic or organic/inorganic hybrid materials and exhibit several unique photophysical properties. They have potential for use in a variety of technological applications. These include use in display technology and photovoltaic cells. One major technical hurdle that has inhibited in-depth characterization and further application of these materials in industry has been their rather very limited stability. To address this issue, the Mattoussi and Ma groups are designing and optimizing a set of coordinating polymers that present either zwitterion or cation/anion anchors. The ligand design offers flexibility in controlling the number, structure and properties of the coordinating motifs as well as the solubilizing blocks, providing polymers that can tightly interact with the nanocrystal surfaces. Such coatings can impart steric stability to these materials over a wide range of conditions, preserve the nanocrystal integrity and potentially enhance their optical and electronic properties. The present project is interdisciplinary in nature, and as such, it provides opportunities for training students in several areas of materials chemistry, spectroscopy, and device engineering.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.