Tuning Energetic Levels in Nanocrystal Quantum Dots through Surface Manipulations

Soreni-Harari, Michal; Yaacobi‐Gross, Nir; Steiner, D.; Aharoni, Assaf; Banin, Uri; Millo, Oded; Tessler, Nir

doi:10.1021/nl0732171

Cited by 172 publications

(203 citation statements)

References 33 publications

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“…Similar results have been reported for CdSe and InAs nanoparticles with VBM shifts of as much as 0.4 eV depending on the ligand. 60,61,63 In the case of CdSe, it was suggested that these differences may be explained by the degree of hole scavenging and surface passivation. A ligand with suitable trap sites for holes or poor binding affinity and incomplete surface site passivation (thiols, pyridine) was found to induce a lower VBM position than ligands without these properties (primary amines in the case of CdSe).…”

Section: * S Supporting Informationmentioning

confidence: 99%

Direct Work Function Measurement by Gas Phase Photoelectron Spectroscopy and Its Application on PbS Nanoparticles

Axnanda

Scheele²,

Crumlin³

et al. 2013

Nano Lett.

132

119

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Work function is a fundamental property of a material's surface. It is playing an ever more important role in engineering new energy materials and efficient energy devices, especially in the field of photovoltaic devices, catalysis, semiconductor heterojunctions, nanotechnology, and electrochemistry. Using ambient pressure X-ray photoelectron spectroscopy (APXPS), we have measured the binding energies of core level photoelectrons of Ar gas in the vicinity of several reference materials with known work functions (Au(111), Pt(111), graphite) and PbS nanoparticles. We demonstrate an unambiguously negative correlation between the work functions of reference samples and the binding energies of Ar 2p core level photoelectrons detected from the Ar gas near the sample surface region. Using this experimentally determined linear relationship between the surface work function and Ar gas core level photoelectron binding energy, we can measure the surface work function of different materials under different gas environments. To demonstrate the potential applications of this ambient pressure XPS technique in nanotechnology and solar energy research, we investigate the work functions of PbS nanoparticles with various capping ligands: methoxide, mercaptopropionic acid, and ethanedithiol. Significant Fermi level position changes are observed for PbS nanoparticles when the nanoparticle size and capping ligands are varied. The corresponding changes in the valence band maximum illustrate that an efficient quantum dot solar cell design has to take into account the electrochemical effect of the capping ligand as well.

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Section: * S Supporting Informationmentioning

confidence: 99%

Direct Work Function Measurement by Gas Phase Photoelectron Spectroscopy and Its Application on PbS Nanoparticles

Axnanda

Scheele²,

Crumlin³

et al. 2013

Nano Lett.

132

119

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“…These processes increase the device conductance by decreasing the distance between neighboring NCs and therefore reducing the inter-particle tunneling barrier. In some cases, certain ligands donate charge [16,17] and in other cases the NCs energy levels may be modified through ligand exchange chemistry [18][19][20].…”

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confidence: 99%

Charge Transport in Cu₂S Nanocrystals Arrays: Effects of Crystallite Size and Ligand Length

Bekenstein¹,

Elimelech²,

Vinokurov³

et al. 2014

Zeitschrift Für Physikalische Chemie

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Quantum confinement effects are observed in transport measurements of Cu 2 S nanocrystal based devices. Two nanocrystals sizes are studied, 3 nm being in the quantum-confinement regime, and 14 nm, lacking confinement. The effect of ligand length on the charge transport mechanism is studied via conductance temperature dependence measurements. While in the 14 nm nanocrystal based devices unique non-monotonic temperature dependence is observed, the 3 nm based devices show only thermally activated transport for all ligands. The difference is attributed to a cross-over from inter-particle hopping to intra-particle dominated transport as the ligand length increases. In the 3 nm devices the effect of ligand length on the charge-hopping activation energy is also discussed.Keywords: Semiconducting Nanocrystals Arrays, Ligand Exchange, Charge Transport, Copper Sulfide Nanocrystals, Quantum Confinement. Semiconducting nanocrystals (NCs) are studied intensively in the context of solution processed NC based future electronic devices. In addition to the well known synthetic control over composition, size and shape of the NCs [1, 2], the electronic

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“…These tunable properties have been implemented in nanocrystal (NC) based devices made of a single component, 1,2 as a combination of different nanocrystals or compositions, 3 or in hybrid organic-inorganic devices where nanocrystals were interfaced with semiconducting polymers. [4][5][6][7][8][9][10] Despite the progress made in many aspects of nanocrystal's synthesis and devices made of them, there seems to remain an issue that holds back some applications. There are many reports that although the photoluminescence (PL) efficiency of near infrared (NIR) emitting NCs in solution could be 20% or above, the quantum efficiency (QE) measured for solid films is in the range of 1% and often below it.…”

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confidence: 99%

Research Update: Preserving the photoluminescence efficiency of near infrared emitting nanocrystals when embedded in a polymer matrix

Solomeshch

Tessler

2016

APL Materials

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Tuning Energetic Levels in Nanocrystal Quantum Dots through Surface Manipulations

Cited by 172 publications

References 33 publications

Direct Work Function Measurement by Gas Phase Photoelectron Spectroscopy and Its Application on PbS Nanoparticles

Direct Work Function Measurement by Gas Phase Photoelectron Spectroscopy and Its Application on PbS Nanoparticles

Charge Transport in Cu₂S Nanocrystals Arrays: Effects of Crystallite Size and Ligand Length

Research Update: Preserving the photoluminescence efficiency of near infrared emitting nanocrystals when embedded in a polymer matrix

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Tuning Energetic Levels in Nanocrystal Quantum Dots through Surface Manipulations

Cited by 172 publications

References 33 publications

Direct Work Function Measurement by Gas Phase Photoelectron Spectroscopy and Its Application on PbS Nanoparticles

Direct Work Function Measurement by Gas Phase Photoelectron Spectroscopy and Its Application on PbS Nanoparticles

Charge Transport in Cu2S Nanocrystals Arrays: Effects of Crystallite Size and Ligand Length

Research Update: Preserving the photoluminescence efficiency of near infrared emitting nanocrystals when embedded in a polymer matrix

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Charge Transport in Cu₂S Nanocrystals Arrays: Effects of Crystallite Size and Ligand Length