Terahertz HgTe Nanocrystals: Beyond Confinement

Goubet, Nicolas; Jagtap, Amardeep; Livache, Clément; Martinez, Bertille; Portalès, Hervé; Xu, Xiang; Lobo, R. P. S. M.; Dubertret, Benoît; Lhuillier, Emmanuel

doi:10.1021/jacs.8b02039

Cited by 122 publications

(165 citation statements)

References 43 publications

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“…A clear resonant behavior was observed in the spectra of HgTe colloidal quantum dots with a broad range of diameters (5-200 nm) [108] and assigned as an intraband/plasmonic peak. A clear resonant behavior was observed in the spectra of HgTe colloidal quantum dots with a broad range of diameters (5-200 nm) [108] and assigned as an intraband/plasmonic peak.…”

Section: Wwwadvopticalmatdementioning

confidence: 96%

Terahertz Spectroscopy of Nanomaterials: a Close Look at Charge‐Carrier Transport

Kužel

Němec

2019

Advanced Optical Materials

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Transport of charges is a fundamental process in many high-tech applications including photovoltaic or optoelectronic devices, but also in more ordinary components such as unsophisticated wires and other circuitry. The development of nanotechnologies resulted in the fabrication of highly complex materials consisting of a large variety of nanosized elements, which inevitably involve a multitude of charge transport processes occurring on various time-and length-scales. Figure 1 summarizes the most common nanoelements with high application potential.For example, the electrodes employed in Grätzel solar cells [1] are composed of percolated networks of a huge number of metal oxide nanoparticles (top-left panel in Figure 1). Colloidal nanocrystals form the basis for thin film electronics and flexible electronic devices. [2] The synthetic approaches control their composition, size and electronic structure (energy levels, density of states within the bands and in the bandgap) and the charge-carrier transport. [2,3] Nanowires and nanotubes made of conventional semiconductors are quasi 1D systems combining Terahertz spectroscopy has been used for almost two decades for investigations of nanomaterials, including nanocrystals, nanoparticles, nanowires, nanotubes or 2D crystals. Its great importance stems from the fact that it is a noncontact method and, owing to its high frequency and broadband character, it is capable of characterizing charge transport properties within individual nano-objects but also among them. In addition, probing of photoinitiated ultrafast charge dynamics is possible thanks to the sub-picosecond time resolution. Despite this unprecedented potential, the interpretation of the measured terahertz conductivity spectra in many materials is still intensively debated. Herein is presented a review of the experiments performed on nanostructures of conventional semiconductors and on carbon nanomaterials (graphene and carbon nanotubes) during the past decade. The state of the art of the theoretical formalism is provided and discussed, including the intrinsic response, as well as the role of inherent heterogeneity and of the experimental conditions.

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Section: Wwwadvopticalmatdementioning

confidence: 96%

Terahertz Spectroscopy of Nanomaterials: a Close Look at Charge‐Carrier Transport

Kužel

Němec

2019

Advanced Optical Materials

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“…[32][33] In particular, CdTe, HgTe as well as Hg x Cd 1-x Te NCs with narrow band gaps are considered as promising candidates for optoelectronic and particularly infrared photodetector materials. [13,[34][35][36][37][38] Compared to well-studied application of isotropic semiconductor QDs or NCs on optoelectronic devices, rod-like structure materials may exhibite extrodinary optical properties due to the polarized properties. [39][40] Au nanorods (NRs), due to their tailorable surface plasmon resonances (SPR) in the near-infrared (NIR) spectral region, [23,[41][42] offer favorable enhancement of the optical performance when coupled with semicondcutor NCs as hybrid structures.…”

Section: Introductionmentioning

confidence: 99%

Au@HgxCd1-xTe core@shell nanorods by sequential aqueous cation exchange for near-infrared photodetectors

Iqbal

et al. 2019

Nano Energy

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We have explored the synthesis of Au@Hg x Cd 1-x Te core@shell nanorods by sequential aqueous cation exchange (ACE) for near-infrared photodetector application. A number of related Au@telluride core/shell nanorod structures were put forwarded, taking advantage of multi-step transformations through a binary and then a ternary phase for the telluride shells. The latter have a high degree of crystallinity thanks to the step-wise ACE method. The use of only trace amounts of Cd 2+ coordinated with tri-n-butylphosphine, assisted the phase transformation from an amorphous Ag 2 Te shell to a highly crystalline Ag 3 AuTe 2 shell in the first stage; this was followed by a further cation exchange (CE) step with far higher Cd 2+ levels to fabricate a highly crystalline CdTe shell, and with an additional CE with Hg 2+ to convert it to a Hg x Cd 1-x Te shell. The composition of the shell components and the well-controlled thickness of the shells enabled tunable surface plasmon resonance properties of the Au@telluride nanorods in the NIR region. Utilizing the enhanced NIR absorption, a hybrid photodetector structure of Au@Hg x Cd 1-x Te nanorods on graphene was fabricated, showing visible to NIR (vis-NIR) broadband detection with high photoresponsivity (~10 6 A/W).

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“…There are several ways to synthesize colloidal QDs, which are reviewed elsewhere [3][4][5][6][7][8][9]. The main method, hot injection, follows a reaction pathway as described by La Mer's model of nucleation and growth [10].…”

Section: Introductionmentioning

confidence: 99%

Quantum Dot Solar Cells: Small Beginnings Have Large Impacts

2018

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From a niche field over 30 years ago, quantum dots (QDs) have developed into viable materials for many commercial optoelectronic devices. We discuss the advancements in Pb-based QD solar cells (QDSCs) from a viewpoint of the pathways an excited state can take when relaxing back to the ground state. Systematically understanding the fundamental processes occurring in QDs has led to improvements in solar cell efficiency from ~3% to over 13% in 8 years. We compile data from ~200 articles reporting functioning QDSCs to give an overview of the current limitations in the technology. We find that the open circuit voltage limits the device efficiency and propose some strategies for overcoming this limitation.

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Terahertz HgTe Nanocrystals: Beyond Confinement

Cited by 122 publications

References 43 publications

Terahertz Spectroscopy of Nanomaterials: a Close Look at Charge‐Carrier Transport

Terahertz Spectroscopy of Nanomaterials: a Close Look at Charge‐Carrier Transport

Au@HgxCd1-xTe core@shell nanorods by sequential aqueous cation exchange for near-infrared photodetectors

Quantum Dot Solar Cells: Small Beginnings Have Large Impacts

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