Violet-to-Blue Gain and Lasing from Colloidal CdS Nanoplatelets: Low-Threshold Stimulated Emission Despite Low Photoluminescence Quantum Yield

• DOI: 10.1021/acsphotonics.6b00890
• Publication Date: 2017-02-01T15:51:41Z
• Authors: Benjamin T. Diroll; Dmitri V. Talapin; Richard D. Schaller
• Keywords: Amplified spontaneous emission; Quantum yield

Amplified spontaneous emission (ASE) and lasing from solution-processed materials are demonstrated in the challenging violet-to-blue (430–490 nm) spectral region for colloidal nanoplatelets of CdS newly synthesized core/shell CdS/ZnS nanoplatelets. Despite modest band-edge photoluminescence quantum yields 2% or less single excitons, which we show results hole trapping, samples exhibit low ASE thresholds. Furthermore, four-monolayer at shorter wavelengths than any reported film quantum-confined material. This work underlines that excitons do not necessarily lead to a poor gain medium. The thresholds originate negligible dispersion thickness, large absorption cross sections 2.8 × 10–14 cm–2, rather slow (150 300 ps) biexciton recombination. We under higher-fluence excitation, can kinetically outcompete trapping. Using as medium, is observed linear optical cavity. confirms fundamental advantages well structures media, even absence high efficiency.