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Quantum-Dot Plasmonics and Spasers

Final Report Summary - QUADOPS (Quantum-Dot Plasmonics and Spasers)

The aim of this ERC Advanced Grant was to combine highly fluorescent semiconductor nanoparticles (known as colloidal quantum dots) with high-quality patterned metallic surfaces to investigate novel phenomena and create optoelectronic devices. In particular, the project studied the creation of "spasers," which are laser-like devices that output surface-plasmon waves instead of photons. Spasers can provide a novel nanoscale source of photons and/or intense nanoscale electromagnetic fields, depending on the design. Such intense local fields can be exploited in on-chip devices for sensing, signal processing, etc. During the project, the team succeeded in combining quantum dots with metallic surfaces to create spasers. In addition, because the quantum dots play a critical role in these devices, they studied several new types of semiconductor nanopartices for use in spasers. Through this effort, they resolved a mystery behind the growth of a recently discovered class of quantum dots (known as nanoplatelets). Nanoplatelets are important for applications because they provide spectrally pure colors for displays. They can also be used as efficient materials in lasers and spasers. The knowledge gained from this project is broadening this class of materials. Secondly, they unraveled the mystery behind the extreme brightness of another recently discovered class of nanocrystals (made from cesium lead halide perovskites). With their collaborators, they discovered that these nanocrystals are the first known semiconductor to avoid the "dark-exciton" problem, which can inhibit light emission from semiconductor nanostructures. By understanding the mechanism behind the brightness of perovskite nanocrystals, this project has provided previously unknown strategies to engineer extremely bright emitters in the future.