Superfluorescence in Lead Halide Perovskite Nanocrystal Assemblies and Giant Nanocrystals
Cesium lead halide nanocrystals can be arranged in various kinds of superlattices by drying-mediated self-assembly using mono, binary and ternary nanocrystal compounds. Due to their small inhomogeneous emission energy spread, large oscillator strength and long dephasing times, we observe characteristic signatures of coherent, cooperative light emission, so-called superfluorescence . The versatility of the material platform allows us to control the superfluorescent properties by changing the superlattice geometry . Furthermore, in order to harness even more enhanced oscillator strength and narrower ensemble linewidth, we study giant nanocrystals of 50 – 200 nm size that are synthesized using ligand-assisted precipitation (LARP). With thin films of these bulk-like crystals where the excitons are clearly in the weak confinement regime, we observe signatures of superfluorescence at about an order of magnitude lower excitation power. Moreover, we investigate the emission properties in different excitation geometries and explore the cross-over to amplified spontaneous emission (ASE) at elevated temperatures. Acknowledgements: We acknowledge partial funding by the Swiss National Science Foundation (grant number 200021_192308, project Q-Light). References:  Rainò, G.; Becker, M. A.; Bodnarchuk, M. I.; Mahrt, R. F.; Kovalenko, M. V.; Stöferle, T. Superfluorescence from Lead Halide Perovskite Quantum Dot Superlattices. Nature 2018, 563, 671.  Cherniukh, I.; Rainò, G.; Stöferle, T.; Burian, M.; Travesset, A.; Naumenko, D.; Amenitsch, H.; Erni, R.; Mahrt, R. F.; Bodnarchuk, M. I.; Kovalenko, M. V. Perovskite-Type Superlattices from Lead Halide Perovskite Nanocubes. Nature 2021, 593, 535.