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

Klepzig, Lars F.; Biesterfeld, Leon; Romain, Michel; Niebur, André; Schlosser, Anja; Hübner, Jens; Lauth, Jannika

doi:10.1039/d1na00704a

Cited by 17 publications

(33 citation statements)

References 73 publications

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“…37 Ultrafast carrier dynamics were studied by broadband pump-probe spectroscopy in a set-up described previously and briefly discussed here. 37,62,63 100 fs laser pulses with a central wavelength of 800 nm are generated by a Ti:sapphire amplifier system (Spectra-Physics, Spitfire ACE) and split in two parts in order to get pump and probe (90:10). The pump beam wavelength is adjustable from 300 nm to 2100 nm by nonlinear frequency mixing in an optical parametric amplifier and second harmonics generation system (TOPAS).…”

Section: Optoelectronic Properties and Exciton Dynamics Of Mos 2 Nano...mentioning

confidence: 99%

Untangling the Intertwined: Metallic to Semiconducting Phase Transition in Colloidal MoS2 Nanoplatelets and Nanosheets

Niebur

Söll

Haizmann

et al. 2022

Preprint

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Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have a thickness-tunable band gap in the semiconducting crystal phase and – in monolayer form – exhibit a direct band gap. TMDCs are highly promising for spin- and valleytronics and show an ultrafast response to external (optical) stimuli, an essential feature for optoelectronics. However, up to now, colloidal synthesis routes for ultrathin TMDCs typically yield different shapes and crystal phases and a thorough understanding of the product guiding reaction mechanism is missing. We investigate the colloidal synthesis of ultrathin MoS2 nanoplatelets (8 nm ± 4 nm) and nanosheets (22 nm ± 9 nm) in terms of the evolution of crystal phase and shape over the course of their formation. The reaction is followed by X-ray photoelectron spectroscopy, showing that a mixture of the semiconducting 2H and the metallic 1T crystal phase is formed initially, regardless of the molybdenum oleate precursor concentration used for the reaction. A low precursor concentration however leads to the formation of MoS2 nanoplatelets, while a high concentration yields laterally larger MoS2 nanosheets. Both structures have undergone a full transition to the semiconducting 2H crystal phase by the end of the reaction. Phase pure semiconducting MoS2 nanoplatelets with a lateral size approaching the MoS2 exciton Bohr radius exhibit strong additional lateral quantum confinement leading to a drastically shortened decay of the B-exciton, which we characterize by ultrafast transient absorption spectroscopy. Our results offer a straight-forward synthesis strategy to phase pure semiconducting 2D MoS2 and represent an important starting point for chemically exploring upcoming colloidal TMDC heterostructures for optical applications.

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Section: Optoelectronic Properties and Exciton Dynamics Of Mos 2 Nano...mentioning

confidence: 99%

Untangling the Intertwined: Metallic to Semiconducting Phase Transition in Colloidal MoS2 Nanoplatelets and Nanosheets

Niebur

Söll

Haizmann

et al. 2022

Preprint

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“…Along with quantum wells (QWs) and quantum dots (QDs), semiconductor NPLs are the next generation of semiconductor nanostructures with the maximum possible miniaturization of the sample in the growth direction. One of the most intensively and successfully studied objects in this area are semiconductor NPLs of II-VI compounds with wurtzite or zinc blende structure (CdS, CdSe, CdTe [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ], HgSe, HgTe [ 21 , 22 ]) and, partly, compounds IV–VI (PbS, PbSe, PbTe [ 4 , 12 , 23 , 24 , 25 ], as well as NPLs based on In, Sn, Cu [ 4 ]). The dimensions of these systems on the plane of the plate can reach from the tens, hundreds or even thousands of angstroms, while in the transverse direction, the thickness of the NPLs can reach only a few atomic layers and is controlled up to a monolayer precision and almost ideal thickness uniformity [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 …”

Section: Introductionmentioning

confidence: 99%

“…When looking at the optical properties of NPLs, the main and most important task is determining the energy spectrum of charge carriers, considering the specifics of the manifestation of size quantization effects and exciton states in the nanostructure under consideration. Regarding these studies, there are currently a very large number of experimental and theoretical works (see, for example, [ 2 , 3 , 4 , 11 , 12 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 28 , 31 , 33 , 34 , 35 ]). The lateral confinement in NPLs leads to the impossibility of the exciton and impurity state motion having an exact analytical description.…”

Section: Introductionmentioning

confidence: 99%

Exciton States and Optical Absorption in CdSe and PbS Nanoplatelets

et al. 2022

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The exciton states and their influence on the optical absorption spectrum of CdSe and PbS nanoplatelets (NPLs) are considered theoretically in this paper. The problem is discussed in cases of strong, intermediate, and weak size quantization regimes of charge carrier motion in NPLs. For each size quantization regime, the corresponding potential that adequately describes the electron–hole interaction in this mode of space quantization of charge carriers is chosen. The single-particle energy spectra and corresponding wave functions for strong intermediate and weak size quantization regimes have been revealed. The dependence of material parameters on the number of monolayers in the sample has been considered. The related selection rules and the dependence of the absorption coefficient on the frequency and polarization direction of the incident light wave were obtained. The interband transition threshold energy dependencies were obtained for each size quantization regime. The effect of dielectric coefficient mismatch and different models of electron–hole interaction potentials have been studied in CdSe and PbS NPLs. It is also shown that with an increase in the linear dimensions of the structure, the threshold frequency of absorption decreases. The binding energies and absorption coefficient results for NPL with different thicknesses agree with the experimental data. The values of the absorption exciton peaks measured experimentally are close to our calculated values for CdSe and PbS samples.

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“…However, only few direct syntheses have yielded PbSe NPLs up to now. 23,36 A recent example from our group is the direct synthesis of colloidal PbSe NPLs from lead oleate and selenourea at 0 °C, reaching a PLQY of 37.4% at 1.27 eV (980 nm). 36 Here, we investigate the influence of different metal halide compounds on the optical properties of 2D PbSe NPLs.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The PbSe NPLs applied exhibit a thickness of 0.8 ± 0.1 nm, and their PL maximum is tunable between 1.43−0.83 eV (860− 1510 nm) via mainly controlling the lateral size of the NPLs. 36 We chose two sets of synthetic parameters, which result in the formation of PbSe NPLs that exhibit a PL maximum near the two ends of the tunable energy range at 1.36 eV (912 nm) and 0.98 eV (1265 nm). Previous work on the surface treatment and passivation has been focused on NCs 9,37−39 and Cd-based NPLs with PL mainly in the visible region.…”

Section: ■ Introductionmentioning

confidence: 99%

Toward Bright Colloidal Near-Infrared Emitters: Surface Passivation of 2D PbSe Nanoplatelets by Metal Halides

et al. 2022

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Colloidal 2D PbSe nanoplatelets (NPLs) are promising near- and short wave-infrared emitters for optoelectronic applications at telecommunication wavelengths. However, their photoluminescence quantum yield (PLQY) is limited by the ubiquitous presence of surface-related trap states. Here, we apply a treatment of colloidal PbSe NPLs with different metal halides (MX2, M = Zn, Cd, Pb; X = F, Cl, Br, I) to improve their emission brightness. A surface passivation of the NPLs by PbI2 leads to the best results with a strongly increased PLQY (27% for PbSe NPLs emitting at 0.98 eV (1265 nm) and up to 61% for PbSe NPLs emitting at 1.25 eV (989 nm)). Simultaneously, the full width at half-maximum of the NPL photoluminescence decreased by 10% after the treatment. X-ray photoelectron spectroscopy and complementary surface treatment of PbSe NPLs with organic halides reveal the combined passivating role of both X-type binding halides X– and Z-type binding metal halides MX2 in enhancing the optical properties of the PbSe NPLs. Our results emphasize the potential of 2D PbSe NPLs for efficient emission tailored for the application in fiber optics.

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

Abstract: Colloidal two-dimensional (2D) lead chalcogenide nanoplatelets (NPLs) represent highly interesting materials for near- and short wave-infrared applications including innovative glass fiber optics exhibiting negligible attenuation. In this work, we demonstrate...

Cited by 17 publications

References 73 publications

Untangling the Intertwined: Metallic to Semiconducting Phase Transition in Colloidal MoS2 Nanoplatelets and Nanosheets

Untangling the Intertwined: Metallic to Semiconducting Phase Transition in Colloidal MoS2 Nanoplatelets and Nanosheets

Exciton States and Optical Absorption in CdSe and PbS Nanoplatelets

Toward Bright Colloidal Near-Infrared Emitters: Surface Passivation of 2D PbSe Nanoplatelets by Metal Halides

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