Stimulated Emission and Lasing from Bulk CdSe Nanocrystals.

Nanocrystals with a size in the regime of vanishing quantum confinement, or bulk nanocrystals (BNCs), have emerged recently as viable solution processable optical gain materials in the green part of the spectrum. Here, we show that these properties can be extended to the crucial red region using CdSe BNCs. Through quantitative time-resolved spectroscopy, we can model these nanocrystals as bulk semiconductors, thereby revealing that the gain originates from an unbound electron-hole plasma state.

Optical gain and lasing from bulk cadmium sulfide nanocrystals through bandgap renormalization.

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 with best-in-class gain thresholds below a single exciton per nanocrystal and 3 ns gain lifetimes not limited by non-radiative Auger processes.