Ag<sub>2</sub>ZnSnS<sub>4</sub>–ZnS core–shell colloidal quantum dots: a near-infrared luminescent material based on environmentally friendly elements

Saha, Avijit; Konstantatos, Gerasimos

doi:10.1039/d1tc00421b

Cited by 15 publications

(13 citation statements)

References 34 publications

(50 reference statements)

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“…This is a considerably shorter emission wavelength than previous reports (cf. 740 nm), [11][12] and is consistent with strong quantum confinement in ultra-small particles. The emission spectra also show a slight shoulder near 800 nm (consistent with α-Ag2S, vide supra) that is observable in the 10s aliquot, but is no longer observed 5 minutes after injection.…”

Section: A Stepwise Reaction Achieves Ultra-small Azts Ncsmentioning

confidence: 62%

“…11 Initial reports have confirmed red/near-infrared emission that can be improved through the growth of a ZnS shell, and tuned between 740-850 nm via size-controlled synthesis that exploit quantum confinement. 12 This red/near-infrared wavelength range is of particular interest for application such as thin-film photodetectors and NC-sensitized triplet fusion upconversion, where Pb-based NCs have been dominant. 1,3,[13][14][15] Thus, AZTS NCs stand as an intriguing candidate for a new generation of greener optoelectronic devices.…”

Section: Introductionmentioning

confidence: 99%

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A Stepwise Reaction Achieves Emissive, Ultra-Small Ag2ZnSnS4 Nanocrystals

Villanueva

Hasham

Green

et al. 2023

Preprint

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Pirquitasite Ag2ZnSnS4 (AZTS) nanocrystals (NCs) are emergent, lead-free emissive materials in the coinage chalcogenide family with applications in optoelectronic technologies. Like many multinary nanomaterials, their phase-pure synthesis is complicated by the generation of e.g. binary/ternary chalcogenide and metallic impurities. Here, we develop a stepwise synthetic procedure that controls the size, morphology, and transformations of acanthite (Ag2S) and canfieldite (Ag8SnS6) intermediates. This reaction scheme improves size-dispersity and grants the production of small AZTS NCs (d: 2.1-4.0 nm) that have not been achieved through established single-injection procedures expanding the accessible quantum-confined AZTS emission to shorter wavelengths (650-740 nm). We show that the initial sulfur stoichiometry is the key handle for template-size tunability and reveal that temporally separating transformation steps is crucial to obtaining <740 nm emitting AZTS NCs. We then use NMR and optical spectroscopies to demonstrate that the installation of thiol ligands improves colloidal stability and photoluminescence, while carboxylate ligands do not. Finally, facilitated by this enhanced synthetic control, we show that our ultra-small AZTS NCs can act as effective and less-toxic sensitizers for red-to-blue triplet fusion upconversion. Our results highlight transferrable insights for the synthesis and post-synthetic treatment of complex less-toxic quaternary nanocrystalline systems.

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Section: A Stepwise Reaction Achieves Ultra-small Azts Ncsmentioning

confidence: 62%

Section: Introductionmentioning

confidence: 99%

A Stepwise Reaction Achieves Emissive, Ultra-Small Ag2ZnSnS4 Nanocrystals

Villanueva

Hasham

Green

et al. 2023

Preprint

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“…Therefore, the small red-shifted emission of the bare InP QDs can be attributed to the possible spreading of the electron wave function through the small energy barrier between the core and shell material and the formation of a slight quasi type-II structure (Scheme S2). − However, it is evident that the effect of carrier confinement is prevalent rather than the leakage of the excitons into the shell.…”

Section: Resultsmentioning

confidence: 99%

Deep Blue and Highly Emissive ZnS-Passivated InP QDs: Facile Synthesis, Characterization, and Deciphering of Their Ultrafast-to-Slow Photodynamics

Rakshit

Cohen

Gutiérrez

et al. 2023

ACS Appl. Mater. Interfaces

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InP-based quantum dots (QDs) are an environment-friendly alternative to their heavy metal-ion-based counterparts. Herein we report a simple procedure for synthesizing blue emissive InP QDs using oleic acid and oleylamine as surface ligands, yielding ultrasmall QDs with average sizes of 1.74 and 1.81 nm, respectively. Consecutive thin coating with ZnS increased the size of these QDs to 4.11 and 4.15 nm, respectively, alongside a significant enhancement of their emission intensities centered at ∼410 nm and ∼430 nm, respectively. Pure phase synthesis of these deep-blue emissive QDs is confirmed by powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Armed with femtosecond to millisecond time-resolved spectroscopic techniques, we decipher the energy pathways, reflecting the effect of successive ZnS passivation on the charge carrier (electrons and holes) dynamics in the deep-blue emissive InP, InP/ZnS, and InP/ZnS/ZnS QDs. Successive coating of the InP QDs increases the intraband relaxation times from 200 to 700 fs and the lifetime of the hot electrons from 2 to 8 ps. The lifetime of the cold holes also increase from 1 to 4 ps, and remarkably, the Auger recombination escalates from 15 to 165 ps. The coating also drastically decreases the quenching by the molecular oxygen of the trapped charge carriers at the surfaces of the QDs. Our results provide clues to push further the emission of InP QDs into more energetically spectral regions and to increase the fluorescence quantum yield, targeting the construction of efficient UV-emissive light-emitting devices (LEDs).

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“…The synthesis of size-controlled QDs has been extensively studied. [62][63][64] In many specific applications, very small QDs are needed to obtain the desired properties. However, particles with very small diameters (o2 nm) are unstable.…”

Section: Alloyed Structurementioning

confidence: 99%

Synthesis and structure design of I–III–VI quantum dots for white light-emitting diodes

Zhou

et al. 2022

Mater. Chem. Front.

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Ag₂ZnSnS₄–ZnS core–shell colloidal quantum dots: a near-infrared luminescent material based on environmentally friendly elements

Abstract: . Low cost, multinary colloidal quantum dots (QDs), based on environmentally friendly elements, with bright, narrow-width, tunable near-infrared (NIR) luminescence are promising alternatives to Cd and Pb chalcogenide QDs for...

Cited by 15 publications

References 34 publications

A Stepwise Reaction Achieves Emissive, Ultra-Small Ag2ZnSnS4 Nanocrystals

A Stepwise Reaction Achieves Emissive, Ultra-Small Ag2ZnSnS4 Nanocrystals

Deep Blue and Highly Emissive ZnS-Passivated InP QDs: Facile Synthesis, Characterization, and Deciphering of Their Ultrafast-to-Slow Photodynamics

Synthesis and structure design of I–III–VI quantum dots for white light-emitting diodes

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Ag2ZnSnS4–ZnS core–shell colloidal quantum dots: a near-infrared luminescent material based on environmentally friendly elements

Abstract: . Low cost, multinary colloidal quantum dots (QDs), based on environmentally friendly elements, with bright, narrow-width, tunable near-infrared (NIR) luminescence are promising alternatives to Cd and Pb chalcogenide QDs for...

Cited by 15 publications

References 34 publications

A Stepwise Reaction Achieves Emissive, Ultra-Small Ag2ZnSnS4 Nanocrystals

A Stepwise Reaction Achieves Emissive, Ultra-Small Ag2ZnSnS4 Nanocrystals

Deep Blue and Highly Emissive ZnS-Passivated InP QDs: Facile Synthesis, Characterization, and Deciphering of Their Ultrafast-to-Slow Photodynamics

Synthesis and structure design of I–III–VI quantum dots for white light-emitting diodes

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Product

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Ag₂ZnSnS₄–ZnS core–shell colloidal quantum dots: a near-infrared luminescent material based on environmentally friendly elements