Brightly Luminescent Core/Shell Nanoplatelets with Continuously Tunable Optical Properties. Issue 7 (24th January 2019)

• Record Type: Journal Article
• Authors: Meerbach, Christian; Tietze, Remo; Voigt, Sascha; Sayevich, Vladimir; Dzhagan, Volodymyr M.; Erwin, Steven C.; Dang, Zhiya; Selyshchev, Oleksandr; Schneider, Kristian; Zahn, Dietrich R. T.; Lesnyak, Vladimir; Eychmüller, Alexander
• Is Part Of: Advanced optical materials. Volume 7:Issue 7(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-01-24
• Subjects: cadmium selenide -- colloidal semiconductor nanoplatelets -- color tuning -- photoluminescence -- surface modification; Optical materials -- Periodicals; Photonics -- Periodicals; 620.11295
• DOI: 10.1002/adom.201801478
• Languages: English
• ISSNs: 2195-1071

Abstract

Abstract: A straightforward, rapid method to create colloidally stable and brightly luminescent core/shell CdSe‐based nanoplatelets (NPLs) with fluorescence quantum yields (QYs) up to 50% is demonstrated. A layer‐by‐layer deposition technique is used which is based on a two‐phase mixture—consisting of a nonpolar phase, which includes the NPLs, and a saturated ionic polar phase—to separate the reagents and hinder the nucleation of the shell material. The deposition of the first sulfur layer leads to a significant redshift (by more than 100 nm) of the optical absorption and emission of the NPLs. Hence, by varying either the sulfur precursor content or the reaction time, one can precisely and continuously tune the absorption and emission maxima from 520 to 630 nm. This evolution of the absorption onset during the shell growth is explained quantitatively using density‐functional theory and atomistic statistical simulations. The emission can be further enhanced by exposure of the NPL solution to ambient sunlight. Finally, it is demonstrated that the core/shell NPLs can be transferred from the organic solution to aqueous media with no reduction of their QY, which opens the door to a broad range of practical applications. Abstract : A straightforward colloidal synthesis of core/shell CdSe/Cd(Zn)S nanoplatelets with continuously and precisely tunable fluorescence in the range of 520–630 nm is demonstrated. The shells are grown by alternate deposition of sulfur and cadmium (and/or zinc) layers in a two‐phase mixture at room temperature. The addition of the first sulfur layer leads to a significant redshift of the optical features of the nanoplatelets.