Letter | Published:

Continuous-wave biexciton lasing at room temperature using solution-processed quantum wells

Nature Nanotechnology volume 9, pages 891895 (2014) | Download Citation

Abstract

Solution-processed inorganic and organic materials have been pursued for more than a decade as low-threshold, high-gain lasing media, motivated in large part by their tunable optoelectronic properties and ease of synthesis and processing1. Although both have demonstrated stimulated emission and lasing, they have not yet approached the continuous-wave pumping regime1,2,3,4,5,6,7,8. Two-dimensional CdSe colloidal nanosheets combine the advantage of solution synthesis with the optoelectronic properties of epitaxial two-dimensional quantum wells. Here, we show that these colloidal quantum wells possess large exciton and biexciton binding energies of 132 meV and 30 meV, respectively, giving rise to stimulated emission from biexcitons at room temperature. Under femtosecond pulsed excitation, close-packed thin films yield an ultralow stimulated emission threshold of 6 μJ cm–2, sufficient to achieve continuous-wave pumped stimulated emission, and lasing when these layers are embedded in surface-emitting microcavities.

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Acknowledgements

The research leading to these results has received funding from the European Union's Seventh Framework Program (FP7/2007-2013, under grant agreement no. 298022, NIRPLANA) and the CARIPLO Foundation (NANOCRYSLAS). M. Scotto is thanked for valuable technical assistance.

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Affiliations

  1. Istituto Italiano di Tecnologia, via Morego 30, IT-16163 Genova, Italy

    • Joel Q. Grim
    • , Sotirios Christodoulou
    • , Francesco Di Stasio
    • , Roman Krahne
    • , Roberto Cingolani
    • , Liberato Manna
    •  & Iwan Moreels

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Contributions

J.Q.G., F.D.S. and I.M. conceived the experiments. S.C. synthesized the CdSe CQwells and measured the optical properties of the CQwells in solution. J.Q.G. and I.M. performed the ultrafast optical spectroscopy and lasing experiments. J.Q.G., S.C. and F.D.S. fabricated the microcavity devices, with F.D.S and R.K. performing structural characterization. J.Q.G., R.C., L.M. and I.M. analysed and interpreted the data. J.Q.G. and I.M wrote the manuscript, with contributions from all authors.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Iwan Moreels.

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DOI

https://doi.org/10.1038/nnano.2014.213

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