|I. Tanghe, M. Samoli, I. Wagner, S. A. Cayan, A. H. Khan, K. Chen, J. Hodgkiss, I. Moreels, D. Van Thourhout, Z. Hens, P. Geiregat
|Optical gain and lasing from bulk cadmium sulfide nanocrystals through bandgap renormalization
|3 (Dimensions.ai - last update: 25/2/2024)
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Strongly confined colloidal quantum dots have been investigated for low-cost light emission and lasing for nearly two decades. However, known materials struggle to combine technologically relevant metrics of low-threshold and long inverted-state lifetime with a material gain coefficient fit to match cavity losses, particularly under electrical excitation. Here we show that bulk nanocrystals of CdS combine an exceptionally large material gain of 50,000 cm−1 with best-in-class gain thresholds below a single exciton per nanocrystal and 3 ns gain lifetimes not limited by non-radiative Auger processes. We quantitatively account for these findings by invoking a strong bandgap renormalization effect, unobserved in nanocrystals to date, to the best of our knowledge. Next, we demonstrate broadband amplified spontaneous emission and lasing under quasi-continuous-wave conditions. Our results highlight the prospects of bulk nanocrystals for lasing from solution-processable materials.
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