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|Title:||Giant alloyed hot injection shells enable ultralow optical gain threshold in colloidal quantum wells||Authors:||Altintas, Yemliha
Sargent, Edward H.
Demir, Hilmi Volkan
|Keywords:||Engineering::Electrical and electronic engineering||Issue Date:||2019||Source:||Altintas, Y., Gungor, K., Gao, Y., Sak, M., Quliyeva, U., Bappi, G., . . . Demir, H. V. (2019). Giant alloyed hot injection shells enable ultralow optical gain threshold in colloidal quantum wells. ACS Nano, 13(9), 10662–10670. doi:10.1021/acsnano.9b04967||Journal:||ACS Nano||Abstract:||As an attractive materials system for high-performance optoelectronics, colloidal nanoplatelets (NPLs) benefit from atomic-level precision in thickness, minimizing emission inhomogeneous broadening. Much progress has been made to enhance their photoluminescence quantum yield (PLQY) and photostability. However, to date, layer-by-layer growth of shells at room temperature has resulted in defects that limit PLQY and thus curtail the performance of NPLs as an optical gain medium. Here, we introduce a hot-injection method growing giant alloyed shells using an approach that reduces core/shell lattice mismatch and suppresses Auger recombination. Near-unity PLQY is achieved with a narrow full-width-at-half-maximum (20 nm), accompanied by emission tunability (from 610 to 650 nm). The biexciton lifetime exceeds 1 ns, an order of magnitude longer than in conventional colloidal quantum dots (CQDs). Reduced Auger recombination enables record-low amplified spontaneous emission threshold of 2.4 μJ cm-2 under one-photon pumping. This is lower by a factor of 2.5 than the best previously reported value in nanocrystals (6 μJ cm-2 for CdSe/CdS NPLs). Here, we also report single-mode lasing operation with a 0.55 mJ cm-2 threshold under two-photoexcitation, which is also the best among nanocrystals (compared to 0.76 mJ cm-2 from CdSe/CdS CQDs in the Fabry-Pérot cavity). These findings indicate that hot-injection growth of thick alloyed shells makes ultrahigh performance NPLs.||URI:||https://hdl.handle.net/10356/140190||ISSN:||1936-0851||DOI:||10.1021/acsnano.9b04967||Rights:||This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS nano, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acsnano.9b04967||Fulltext Permission:||open||Fulltext Availability:||With Fulltext|
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