Electroluminescence from Nanocrystals in an Electromigrated Gap Composed of Two Different Metals

Dorn, August; Huang, Hao; Bawendi, Moungi G.

doi:10.1021/nl080018o

Cited by 11 publications

(16 citation statements)

References 30 publications

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“…To do so nanofabrication is necessary. Nanogap and nanotrench electrodes have been obtained through a variety of methods such as e-beam lithography, electromigration, , or shadowing methods. Nanocrystal-based photodetectors using nanometer-spaced electrodes have been proposed by Prins et al and Willis et al; however, the device keeps operating in the hopping regime since the nanocrystals are not larger that the electrode spacing.…”

Section: Applications and Perspectivesmentioning

confidence: 99%

Two-Dimensional Colloidal Nanocrystals

et al. 2016

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Abstract:In this paper, we review recent progresses on colloidal growth of 2D nanocrystals.We identify four main sources of anisotropy which lead to the formation of plate-and sheetlike colloidal nanomaterials. Defect induced anisotropy is a growth method which relies on the presence of topological defects at the nanoscale to induce 2D shapes objects. Such a method is particularly important in the growth of metallic nanoobjects. Another way to induce anisotropy is based on ligand engineering. The availability of some nanocrystal facets can be tuned by selectively covering the surface with ligands of tunable thickness. Cadmium chalcogenides nanoplatelets (NPLs) strongly rely on this method which offers atomic control in the thinner direction, down to a few monolayers. 2D objects can also be obtained by post or in situ self-assembly of nanocrystals. This growth method differs from the previous ones in the sense that the elementary objects are not molecular precursors, and is a common method for lead chalcogenide compounds. Finally, anisotropy may simply rely on the lattice anisotropy itself as it is common for rod-like nanocrystals. Colloidally grown Transition Metal DiChalcogenides (TMDC) in particular result from such process. We also present hybrid syntheses which combine several of the previously described methods and other paths, such as cation exchange, which expand the range of available materials. Finally, we discuss in which sense 2D-objects differ from 0D nanocrystals and review some of their applications in optoelectronics, including lasing and photodetection, and biology.

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Section: Applications and Perspectivesmentioning

confidence: 99%

Two-Dimensional Colloidal Nanocrystals

et al. 2016

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“…Another approach, which permits the colloids to keep their charge transport signature, is the use of electrodes separated by a few nanometers only, electrically addressing a single nanoparticle . In this particular situation, the short transport length also reduces the carrier’s transmit time, which positively impacts the photoconductive gain of the device. , Several methods have been proposed to realize these nanogaps, such as e-beam lithography, , self-alignment method, , and electromigration, , to name a few. Making contact with a single nanoparticle provides unique insight into fundamental understanding and eliminates the complications associated with the hopping-assisted percolating mechanism but suffers from severe drawbacks.…”

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confidence: 99%

Nanoplatelets Bridging a Nanotrench: A New Architecture for Photodetectors with Increased Sensitivity

Lhuillier¹,

Dayen

Thomas

et al. 2015

Nano Lett.

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Interparticle charge hopping severely limits the integration of colloidal nanocrystals films for optoelectronic device applications. We propose here to overcome this problem by using high aspect ratio interconnects made of wide electrodes separated by a few tens of namometers, a distance matching the size of a single nanoplatelet. The semiconducting CdSe/CdS nanoplatelet coupling with such electrodes allows an efficient electron-hole pair dissociation despite the large binding energy of the exciton, resulting in optimal photoconductance responsivity. We report the highest responsivity obtained so far for CdSe colloidal material with values reaching kA·W(-1), corresponding to eight decades of enhancement compared to usual micrometer-scaled architectures. In addition, a decrease of 1 order of magnitude of the current noise is observed, revealing the reduced influence of the surface traps on transport. The nanotrench geometry provides top access to ion gel electrolyte gating, allowing for a photoresponsive transistor with 10(4) on/off ratio. A simple analytical model reproduces the device behavior and underlines the key parameters related to its performance.

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“…This dramatic broadening of the spectral output in EL as compared with P L has been observed in many previous studies involving a range of materials. [3,15,28,14,18,46] A second characteristic feature of EL emission in tn-ELJs, already seen in Figure 2.6, is that the EL produced within a 20 µm wide element consists of a series of sub-micron point emitters -even at high E app . This is apparent in the images and plots of Figure 2.8b that show emission from a w CdSe = 195 nm tn-ELJ at E app from 4.5 V to 13.5 V. One possible reason for localized light emission is modulation of the electric field along the axis of each CdSe nanowire, caused by its width nonuniformity.…”

Section: Electroluminescence Spectra and Mechanismsmentioning

confidence: 99%

Electrodeposited, Transverse Nanowire Electroluminescent Junctions

Qiao

Dutta

et al. 2016

ACS Nano

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The preparation by electrodeposition of transverse nanowire electroluminescent junctions (tn-ELJs) is described, and the electroluminescence (EL) properties of these devices are characterized. The lithographically patterned nanowire electrodeposition process is first used to prepare long (millimeters), linear, nanocrystalline CdSe nanowires on glass. The thickness of these nanowires along the emission axis is 60 nm, and the width, wCdSe, along the electrical axis is adjustable from 100 to 450 nm. Ten pairs of nickel-gold electrical contacts are then positioned along the axis of this nanowire using lithographically directed electrodeposition. The resulting linear array of nickel-CdSe-gold junctions produces EL with an external quantum efficiency, EQE, and threshold voltage, Vth, that depend sensitively on wCdSe. EQE increases with increasing electric field and also with increasing wCdSe, and Vth also increases with wCdSe and, therefore, the electrical resistance of the tn-ELJs. Vth down to 1.8(±0.2) V (for wCdSe ≈ 100 nm) and EQE of 5.5(±0.5) × 10(-5) (for wCdSe ≈ 450 nm) are obtained. tn-ELJs produce a broad EL emission envelope, spanning the wavelength range from 600 to 960 nm.

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Electroluminescence from Nanocrystals in an Electromigrated Gap Composed of Two Different Metals

Cited by 11 publications

References 30 publications

Two-Dimensional Colloidal Nanocrystals

Two-Dimensional Colloidal Nanocrystals

Nanoplatelets Bridging a Nanotrench: A New Architecture for Photodetectors with Increased Sensitivity

Electrodeposited, Transverse Nanowire Electroluminescent Junctions

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