Ultrathin CdSe/CdS and CdSe/ZnS core-shell nanoplatelets: The impact of the shell material on the structure and optical properties

Saidzhonov, Bedil M.; Kozlovsky, V.F.; Зайцев, В. Б.; Vasiliev, R. B.

doi:10.1016/j.jlumin.2019.01.052

Cited by 48 publications

(30 citation statements)

References 53 publications

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“…The third contribution to PL line broadening of the PbSe NPLs may come from the presence of surface defect induced trap states. It was shown that the PL properties (including FWHM) are sensitive to surface modification, including shell growth [ 77 , 78 , 79 , 80 ] and ligand manipulation [ 80 ]. The surface-defect related shallow traps can form a continuum of sublevels that will contribute to the emission and lead to its broadening.…”

Section: Discussionmentioning

confidence: 99%

Temperature-Dependent Photoluminescent Properties of PbSe Nanoplatelets

et al. 2020

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Semiconductor colloidal nanoplatelets (NPLs) are a promising new class of nanostructures that can bring much impact on lightning technologies, light-emitting diodes (LED), and laser fabrication. Indeed, great progress has been made in optimizing the optical properties of the NPLs for the visible spectral range, which has already made the implementation of a number of effective devices on their basis possible. To date, state-of-the-art near-infrared (NIR)-emitting NPLs are significantly inferior to their visible-range counterparts, although it would be fair to say that they received significantly less research attention so far. In this study, we report a comprehensive analysis of steady-state and time-dependent photoluminescence (PL) properties of four monolayered (ML) PbSe NPLs. The PL measurements are performed in a temperature range of 78–300 K, and their results are compared to those obtained for CdSe NPLs and PbSe quantum dots (QDs). We show that multiple emissive states, both band-edge and trap-related, are responsible for the formation of the NPLs’ PL band. We demonstrate that the widening of the PL band is caused by the inhomogeneous broadening rather than homogeneous one, and analyze the possible contributions to PL broadening.

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Section: Discussionmentioning

confidence: 99%

Temperature-Dependent Photoluminescent Properties of PbSe Nanoplatelets

et al. 2020

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“…Furthermore, biaxial strain in the core/shell NPLs owing to the quasi-2D geometry of the core may increase the peak asymmetry. 41 Optical Characterization of Core/Shell NPLs. The influence of the shell composition on the emission was characterized by absorption and emission spectroscopy ( Figure 4).…”

Section: Cdse/cd X Zn 1-x S Core/shell Npls the Above Data Demonstramentioning

confidence: 99%

Compositional Grading for Efficient and Narrowband Emission in CdSe-Based Core/Shell Nanoplatelets

et al. 2019

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Colloidal semiconductor nanoplatelets exhibit exceptionally narrow photoluminescence spectra. This occurs because samples can be synthesized in which all nanoplatelets share the same atomic-scale thickness. As this dimension sets the emission wavelength, inhomogeneous linewidth broadening due to size variation, which is always present in samples of quasi-spherical nanocrystals (quantum dots), is essentially eliminated. Nanoplatelets thus offer improved, spectrally pure emitters for various applications. Unfortunately, due to their non-equilibrium shape, nanoplatelets also suffer from low photo-, chemical, and thermal stability, which limits their use. Moreover, their poor stability hampers the development of efficient synthesis protocols for adding high-quality protective inorganic shells, a well-known strategy to improve the performance of quantum dots. Herein, we report a general synthesis approach to highly emissive and stable core/shell nanoplatelets with various shell compositions, including CdSe/ZnS, CdSe/CdS/ZnS, CdSe/CdxZn1-xS, and CdSe/ZnSe. Motivated by previous work on quantum dots, we find that slow, high-temperature growth of shells containing a compositional gradient reduces strain-induced crystal defects and minimizes the emission linewidth while maintaining good surface passivation and nanocrystal uniformity. Indeed, our best core/shell nanoplatelets (CdSe/CdxZn1-xS) show photoluminescence quantum yields of 90% with linewidths as low as 56 meV (19.5 nm at 655 nm). To confirm the high quality of our different core/shell nanoplatelets for a specific application, we demonstrate their use as gain media in low-threshold ring lasers. More generally, the ability of our synthesis protocol to engineer high-quality shells can help further improve nanoplatelets for optoelectronic devices.

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“…Moreover, it is rather weak for the core-shell and core-crown nanoplatelets. 34,46 We also neglect such effects as nonradiative recombination or exciton dissociation. The role of these effects can be controlled experimentally by measuring the quantum yield of the nanoplatelet.…”

Section: Simulation Model and Comparison To Experimentsmentioning

confidence: 99%