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Title: Lateral Size-Dependent Spontaneous and Stimulated Emission Properties in Colloidal CdSe Nanoplatelets
Authors: Olutas, Murat
Guzelturk, Burak
Kelestemur, Yusuf
Yeltik, Aydan
Delikanli, Savas
Demir, Hilmi Volkan
Keywords: Amplified spontaneous emission
Stimulated emission
Colloidal quantum wells
Semiconductor nanoplatelets
Lateral size
Photoluminescence quantum efficiency
Giant two-photon absorption cross-section
Issue Date: 2015
Source: Olutas, M., Guzelturk, B., Kelestemur, Y., Yeltik, A., Delikanli, S., & Demir, H. V. (2015). Lateral Size-Dependent Spontaneous and Stimulated Emission Properties in Colloidal CdSe Nanoplatelets. ACS Nano, 9(5), 5041-5050.
Series/Report no.: ACS Nano
Abstract: Here, we systematically investigated the spontaneous and stimulated emission performances of solution-processed atomically flat quasi-2D nanoplatelets (NPLs) as a function of their lateral size using colloidal CdSe core NPLs. We found that the photoluminescence quantum efficiency of these NPLs decreases with increasing lateral size while their photoluminescence decay rate accelerates. This strongly suggests that nonradiative channels prevail in the NPL ensembles having extended lateral size, which is well-explained by the increasing number of the defected NPL subpopulation. In the case of stimulated emission the role of lateral size in NPLs influentially emerges both in the single- and two-photon absorption (1PA and 2PA) pumping. In the amplified spontaneous emission measurements, we uncovered that the stimulated emission thresholds of 1PA and 2PA exhibit completely opposite behavior with increasing lateral size. The NPLs with larger lateral sizes exhibited higher stimulated emission thresholds under 1PA pumping due to the dominating defected subpopulation in larger NPLs. On the other hand, surprisingly, larger NPLs remarkably revealed lower 2PA-pumped amplified spontaneous emission thresholds. This is attributed to the observation of a “giant” 2PA cross-section overwhelmingly growing with increasing lateral size and reaching record levels higher than 106 GM, at least an order of magnitude stronger than colloidal quantum dots and rods. These findings suggest that the lateral size control in the NPLs, which is commonly neglected, is essential to high-performance colloidal NPL optoelectronic devices in addition to the vertical monolayer control.
ISSN: 1936-0851
DOI: 10.1021/acsnano.5b01927
Schools: School of Electrical and Electronic Engineering 
School of Physical and Mathematical Sciences 
Rights: © 2015 American Chemical Society. This is the author created version of a work that has been peer reviewed and accepted for publication by ACS Nano, American Chemical Society. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [].
Fulltext Permission: open
Fulltext Availability: With Fulltext
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