Ultrafast Charge Transfer and Upconversion in Zinc β‐Tetraaminophthalocyanine‐Functionalized PbS Nanostructures Probed by Transient Absorption Spectroscopy

Lauth, Jannika; Grimaldi, Gianluca; Kinge, Sachin; Houtepen, Arjan J.; Siebbeles, Laurens D. A.; Scheele, Marcus

doi:10.1002/ange.201707443

Cited by 11 publications

(8 citation statements)

References 41 publications

(16 reference statements)

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“…Ultrafast broadband transient optical absorption spectroscopy was performed on a set-up similar as described in literature. 31,39,40 Briefly, a 100 fs laser pulse train from a Ti:sapphire amplifier system (Spectra-Physics, Spitfire ACE) centered at 800 nm is split (90:10) to generate a pump and a probe beam. A broadband white-light super continuum is generated by nonlinear processes inside a CaF2 or sapphire crystal (320 -1600 nm, Ultrafast, Helios FIRE) with the 10 % share of the fundamental.…”

Section: Transient Absorption Spectroscopy (Tas)mentioning

confidence: 99%

Efficient Infrared Emission of Colloidal PbSe Nanoplatelets by Lateral Size Control

Klepzig

Biesterfeld

Romain

et al. 2021

Preprint

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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 a direct synthesis route for 2D PbSe NPLs with cubic rock salt crystal structure at low reaction temperatures of 0 °C and room temperature. A lateral size tuning of the PbSe NPLs by controlling the temper-ature and by adding small amounts of octylamine to the reaction leads to excitonic absorption features in the range of 800 – 1000 nm (1.6 – 1.3 eV) and narrow photoluminescence (PL) seamlessly covering the broadband infrared spec-tral window of 900 – 1450 nm (1.4 – 0.9 eV). The PL quantum yield of the as-synthesized PbSe NPLs is more than doubled by a postsynthetic treatment with CdCl2 (e.g. from 14.7 % to 37.4 % for NPLs emitting at 980 nm with a FWHM of 214 meV). An analysis of the slightly asymmetric PL line shape of the PbSe NPLs and their characterization by ultrafast transient absorption and time-resolved PL spectroscopy reveal a surface trap related PL contribution which is successfully reduced by the CdCl2 treatment from 40 % to 15 %. Our results open up new pathways for a direct synthesis and straightforward incorporation of colloidal PbSe NPLs as efficient infrared emitters at technologi-cally relevant telecommunication wavelengths.

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Section: Transient Absorption Spectroscopy (Tas)mentioning

confidence: 99%

Efficient Infrared Emission of Colloidal PbSe Nanoplatelets by Lateral Size Control

Klepzig

Biesterfeld

Romain

et al. 2021

Preprint

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“…29,30 The appearance of two additional absorption bands at 710 and 850 nm after ligand exchange with Zn4APc is supporting evidence for a successful surface modification of the CdSe NCs. 31 For a comparison, we display the absorption spectrum of pure Zn4APc in the solid state in Figure 1a (black curve), but note that the details of the spectral absorbance are strongly influenced by the types of aggregates formed in the solid state. These are not necessarily identical in the NC/dye film.…”

Section: Characterization Of Ligand Exchange and Effect Onmentioning

confidence: 99%

Fast, Infrared-Active Optical Transistors Based on Dye-Sensitized CdSe Nanocrystals

Kumar

Liu

Hiller

et al. 2019

ACS Appl. Mater. Interfaces

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We report an optically gated transistor composed of CdSe nanocrystals (NCs), sensitized with the dye zinc β-tetraaminophthalocyanine for operation in the first telecom window. This device shows a high ON/OFF ratio of 6 orders of magnitude in the red spectral region and an unprecedented 4.5 orders of magnitude at 847 nm. By transient absorption spectroscopy, we reveal that this unexpected infrared sensitivity is due to electron transfer from the dye to the CdSe NCs within 5 ps. We show by time-resolved photocurrent measurements that this enables fast rise times during near-infrared optical gating of 47 ± 11 ns. Electronic coupling and accelerated nonradiative recombination of charge carriers at the interface between the dye and the CdSe NCs are further corroborated by steady-state and time-resolved photoluminescence measurements. Field-effect transistor measurements indicate that the increase in photocurrent upon laser illumination is mainly due to the increase in the carrier concentration while the mobility remains unchanged. Our results illustrate that organic dyes as ligands for NCs invoke new optoelectronic functionalities, such as fast optical gating at sub-bandgap optical excitation energies.

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“…To further characterize the nature and dynamics of photoexcited states in pristine and CdCl 2 treated PbS NPLs, we apply ultrafast transient optical absorption (TA) spectroscopy as described in refs. [27][28][29][30] and briefly in the Supporting Information. The samples are photoexcited close to the band edge at 700 nm to prevent dynamic effects by charge carrier cooling and with the same photoexcitation density (2.5 × 10 !"…”

mentioning

confidence: 99%

“…photons/cm 2 ) so that the distribution of the number of excitons in both NPL samples is similar. The shape of the TA spectra in Figure 3 is discussed below on the basis of the terminology of electronic transitions and exciton states obtained from TA studies on PbSe 29,31 and PbS NCs 28,32 . is slightly blue-shifted with respect to the steady-state absorption at 680 nm (see Figure 1) implying a redshift in the excited state absorption due to the formation of biexcitons by the probe pulse.…”

mentioning

confidence: 99%

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

Vázquez

Klepzig

et al. 2021

J. Phys. Chem. Lett.

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Strongly quantum-confined 2D colloidal PbS nanoplatelets (NPLs) are highly interesting materials for near-infrared optoelectronic applications. Here, we use ultrafast transient optical absorption spectroscopy to study the characteristics and dynamics of photoexcited excitons in ultrathin PbS NPLs with a cubic (rock-salt) structure. The NPLs are synthesized at near room temperature from lead oleate and thiourea precursors and show an optical absorption onset at 680 nm (1.8 eV) as well as photoluminescence at 720 nm (1.7 eV). By treating PbS NPLs with CdCl 2 in a postsynthetic step, their photoluminescence quantum yield is strongly enhanced from 1.4 % to 19.4 %.The surface treatment leads to an increased lead to sulfur ratio in the structures and associated reduced non-radiative recombination. Exciton-phonon interactions in pristine and CdCl 2 treated PbS NPLs at frequencies of 1.8 and 2.2 THz are apparent from coherent oscillations in the measured transient absorption spectra. This study is an important step forward in unraveling and controlling the optical properties of IV-VI semiconductor NPLs.

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Ultrafast Charge Transfer and Upconversion in Zinc β‐Tetraaminophthalocyanine‐Functionalized PbS Nanostructures Probed by Transient Absorption Spectroscopy

Cited by 11 publications

References 41 publications

Efficient Infrared Emission of Colloidal PbSe Nanoplatelets by Lateral Size Control

Efficient Infrared Emission of Colloidal PbSe Nanoplatelets by Lateral Size Control

Fast, Infrared-Active Optical Transistors Based on Dye-Sensitized CdSe Nanocrystals

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

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