Probing Excitons in Ultrathin PbS Nanoplatelets with Enhanced Near-Infrared Emission

Vázquez, Francisco Manteiga; Yu, Qianli; Klepzig, Lars F.; Siebbeles, Laurens D. A.; Crisp, Ryan W.; Lauth, Jannika

doi:10.1021/acs.jpclett.0c03461

Cited by 26 publications

(27 citation statements)

References 56 publications

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“…Ultrafast broadband transient optical absorption spectroscopic measurements were performed on a setup similar to that described in the literature. , Briefly, a 100 fs laser pulse train from a Ti/sapphire amplifier system (Spectra-Physics, Spitfire ACE) centered at 800 nm is used and split (90:10) to generate a pump and probe beam. A broadband supercontinuum is generated by non-linear processes inside a CaF 2 or sapphire crystal (320–1600 nm) with 10% of the fundamental.…”

Section: Methodsmentioning

confidence: 99%

Quantum Defects in Fluorescent Carbon Nanotubes for Sensing and Mechanistic Studies

et al. 2021

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Single-wall carbon nanotubes (SWCNT) fluoresce in the nearinfrared (NIR) region and have been assembled with biopolymers such as DNA to form highly sensitive molecular (bio)sensors. They change their fluorescence when they interact with analytes. Despite the progress in engineering these sensors, the underlying mechanisms are still not understood. Here, we identify processes and rate constants that explain the photophysical signal transduction by exploiting sp 3 quantum defects in the sp 2 carbon lattice of SWCNTs. As a model system, we use ssDNA-coated (6,5)-SWCNTs, which increase their NIR emission (E 11 , 990 nm) up to +250% in response to the important neurotransmitter dopamine. In contrast, SWCNTs coated with DNA but with a low number of NO 2 -aryl sp 3 quantum defects decrease both their E 11 (−35%) and defect-related E 11 * emission (−50%) at 1130 nm. Consequently, the interaction with the analyte does not change the radiative exciton decay pathway alone. Furthermore, the fluorescence response of pristine SWCNTs increases with SWCNT length, suggesting that exciton diffusion is affected. The quantum yield of pristine (6,5)-SWCNTs increases in response to the analyte from 0.6 to 1.3% and points to a change in non-radiative rate constants. These experimental results for dopamine and other analytes are explained by a Monte Carlo simulation of exciton diffusion, which supports a change in two non-radiative decay pathways together with an increase in exciton diffusion (three-rate constant model). The combination of such SWCNTs with defects and without defects enables the assembly of ratiometric biosensors with opposing responses at different wavelengths. In summary, we demonstrate how perturbation of a nanomaterial with quantum defects reveals the photophysical mechanism and reverses optical responses of biosensors.

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Section: Methodsmentioning

confidence: 99%

Quantum Defects in Fluorescent Carbon Nanotubes for Sensing and Mechanistic Studies

et al. 2021

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“…The synthesis of PbSe NPLs is based on a method by Manteiga Vázquez et al 29 The precursor formation steps and the reaction were run under inert gas conditions either inside a glovebox or on a Schlenk apparatus. The syntheses at 0 °C were conducted using an ice bath.…”

Section: Methodsmentioning

confidence: 99%

Colloidal 2D PbSe nanoplatelets with efficient emission reaching the telecom O-, E- and S-band

et al. 2022

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“…In such a column structure, excitons can be transported between the close-packed nanoplatelets by FRET, which would be quenched when they encountered nonemissive nanoplatelets. For a deep understanding of the dynamics of photoexcited charge carriers in colloidal nanoplatelets, a combination of TRPL, transient absorption (TA), and terahertz (THz) spectroscopic techniques would be required. − Siebbeles et al studied the decay dynamics of excitons in CdSe/CdS platelets and found that the band-to-band relaxation and the trap-induced decay occurred on a time scale of hundreds of picoseconds . By means of optical pump–terahertz probe spectroscopy, they extracted the frequency-dependent alternating current mobility of colloidal Cd-based nanoplatelets, which displayed a significant decrease compared to the value of its bulk counterpart.…”

Section: Spectroscopic Characterizationsmentioning

confidence: 99%

Colloidal Two-Dimensional Metal Chalcogenides: Realization and Application of the Structural Anisotropy

O’Neill

Lesyuk

et al. 2021

Acc. Chem. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS: Due to the spatial confinement, two-dimensional metal chalcogenides display an extraordinary optical response and carrier transport ability. Solution-based synthesis techniques such as colloidal hot injection and ion exchange provide a cost-effective way to fabricate such low-dimensional semiconducting nanocrystals. Over the years, developments in colloidal chemistry made it possible to synthesize various kinds of ultrathin colloidal nanoplatelets, including wurtzite-and zinc blende-type CdSe, rock salt PbS, black phosphorus-like SnX (X = S or Se), hexagonal copper sulfides, selenides, and even transition metal dichalcogenides like MoS 2 . By altering experimental conditions and applying capping ligands with specific functional groups, it is possible to accurately tune the dimensionality, geometry, and consequently the optical properties of these colloidal metal chalcogenide crystals.Here, we review recent progress in the syntheses of twodimensional colloidal metal chalcogenides (CMCs) and property characterizations based on optical spectroscopy or device-related measurements. The discoveries shine a light on their huge prospect for applications in areas such as photovoltaics, optoelectronics, and spintronics. In specific, the formation mechanisms of two-dimensional CMCs are discussed. The growth of colloidal nanocrystals into a two-dimensional shape is found to require either an intrinsic structural asymmetry or the assist of coexisted ligand molecules, which act as lamellar double-layer templates or "facet" the crystals via selective adsorption. By performing optical characterizations and especially ultrafast spectroscopic measurements on these two-dimensional CMCs, their unique electronic and excitonic features are revealed. A strong dependence of optical transition energies linked to both interband and inter-subband processes on the crystal geometry can be verified, highlighting a tremendous confinement effect in such nanocrystals. With the selfassembly of two-dimensional nanocrystals or coupling of different phases by growing heterostructures, unconventional optical performances such as charge transfer state generation or efficient Forster resonance energy transfer are discovered. The growth of large-scale individualized PbS and SnS nanosheets can be realized by facile hot injection techniques, which gives the opportunity to investigate the charge carrier behavior within a single nanocrystal. According to the results of the device-based measurements on these individualized crystals, structure asymmetry-induced anisotropic electrical responses and Rashba effects caused by a splitting of spin-resolved bands in the momentum space due to strong spin−orbit-coupling are demonstrated. It is foreseen that such geometrycontrolled, large-scale two-dimensional CMCs can be the ideal materials used for designing high-efficiency photonics and electronics.

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Probing Excitons in Ultrathin PbS Nanoplatelets with Enhanced Near-Infrared Emission

Cited by 26 publications

References 56 publications

Quantum Defects in Fluorescent Carbon Nanotubes for Sensing and Mechanistic Studies

Quantum Defects in Fluorescent Carbon Nanotubes for Sensing and Mechanistic Studies

Colloidal 2D PbSe nanoplatelets with efficient emission reaching the telecom O-, E- and S-band

Colloidal Two-Dimensional Metal Chalcogenides: Realization and Application of the Structural Anisotropy

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