Electronic passivation of PbSe quantum dot solids by trimethylaluminum vapor dosing

Ueda, Scott T.; Kwak, Iljo; Abelson, Alex; Wolf, Steven; Qian, Caroline; Law, Matt; Kummel, Andrew C.

doi:10.1016/j.apsusc.2020.145812

Cited by 16 publications

(16 citation statements)

References 45 publications

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“…Desorption of the surface ligands by high-temperature annealing and functionalization of the conductive substrates with linkers such as dithiols is problematic on account of the heat- and air-sensitive PbSe QDs 19 . To minimize the electrical resistance between epi-SL and substrate, a sub-monolayer epi-SL can be deposited on a metallic substrate and observed by STM/STS, but the interaction between the QDs and substrate can strongly affect the electronic bands of the QDs 21 , 22 .…”

Section: Resultsmentioning

confidence: 99%

Emergence of distinct electronic states in epitaxially-fused PbSe quantum dot superlattices

Kavrik

Hachtel

et al. 2022

Nat Commun

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Quantum coupling in arrayed nanostructures can produce novel mesoscale properties such as electronic minibands to improve the performance of optoelectronic devices, including ultra-efficient solar cells and infrared photodetectors. Colloidal PbSe quantum dots (QDs) that self-assemble into epitaxially-fused superlattices (epi-SLs) are predicted to exhibit such collective phenomena. Here, we show the emergence of distinct local electronic states induced by crystalline necks that connect individual PbSe QDs and modulate the bandgap energy across the epi-SL. Multi-probe scanning tunneling spectroscopy shows bandgap modulation from 0.7 eV in the QDs to 1.1 eV at their necks. Complementary monochromated electron energy-loss spectroscopy demonstrates bandgap modulation in spectral mapping, confirming the presence of these distinct energy states from necking. The results show the modification of the electronic structure of a precision-made nanoscale superlattice, which may be leveraged in new optoelectronic applications.

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Section: Resultsmentioning

confidence: 99%

Emergence of distinct electronic states in epitaxially-fused PbSe quantum dot superlattices

Kavrik

Hachtel

et al. 2022

Nat Commun

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“…We conjecture that significant potential barriers are still present between the nanocrystals due to inhomogeneities in the connections. We place our findings in the framework of electronic transport studies that have been reported on these lattices [19,20,28]. Finally we make suggestions to improve the electronic coupling and lower the disorder.…”

Section: Introductionmentioning

confidence: 70%

“…These values are consistent with the values recently reported in the literature on similar PbSe QD solids. [20]. Now, we compare this value with theoretical results.…”

Section: Methodsmentioning

confidence: 85%

Electronic properties of atomically coherent square PbSe nanocrystal superlattice resolved by Scanning Tunneling Spectroscopy

Capiod¹,

Sluijs²,

Boer³

et al. 2021

Nanotechnology

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Rock-salt lead selenide nanocrystals can be used as building blocks for large scale square superlattices via two-dimensional assembly of nanocrystals at a liquid-air interface followed by oriented attachment. Here we report Scanning Tunneling Spectroscopy (STS) measurements of the local density of states of an atomically coherent superlattice with square geometry made from PbSe nanocrystals. Controlled annealing of the sample permits the imaging of a clean structure and to reproducibly probe the band gap and the valence hole and conduction electron states. The measured band gap and peak positions are compared to the results of optical spectroscopy and atomistic tight-binding calculations of the square superlattice band Electronic properties of atomically coherent square PbSe nanocrystal superlattice resolved by Scanning Tunne structure. In spite of the crystalline connections between nanocrystals that induce significant electronic couplings, the electronic structure of the superlattices remains very strongly influenced by the effects of disorder and variability.

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“…To minimize the electrical resistance between epi-SL and substrate, sub-monolayer of epi-SL can be deposited on metallic surfaces and observed by STM/STS, but the interaction between the QDs and substrate strongly affects the electronic band of QDs. 16,17 In this work, this issue was resolved by employing a two-probe STM configuration: one STM probe was placed in the tunneling position with a feedback loop to scan the sample, and the other in contact with a nearby part of the film to bias the epi-SL and collect the tunneling current from the first probe (the geometry is shown schematically in Fig. 2a and Fig.…”

Section: Investigating the Local Electronic Structure With Stm/stsmentioning

confidence: 99%

Emergence of Distinct Electronic States in Epitaxially-Fused PbSe Quantum Dot Superlattices

Kavrik

Hachtel

et al. 2021

Preprint

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Quantum coupling in arrayed nanostructures may induce novel mesoscale properties such as electronic minibands that may lead to applications including high efficiency solar cells. Colloidal PbSe quantum dots (QDs) can self-assemble into epitaxially-fused superlattices (epi-SLs), making them a promising material system to study collective phenomena. In the present study, the presence of distinct local electronic states induced by crystalline necks connecting individual PbSe QDs is documented by several techniques that leads to modulation of the band gap energy across the epi-SL. The energy band gap measured by multi-probe scanning tunneling spectroscopy (STS) shows variation from 0.7 eV at the center of the QDs to 1.1 eV at their necks. Complementary monochromated electron energy-loss spectroscopy (EELS) measurements reveal the presence of distinct electronic states from necks in the epi-SL, confirming the STS measurements and demonstrating band gap modulation in spectral mapping. It is hypothesized that these new electronic states are induced by quantum confinement of carriers in the necks between the QDs, redefining the energy landscape of the PbSe QD epi-SL.

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Electronic passivation of PbSe quantum dot solids by trimethylaluminum vapor dosing

Cited by 16 publications

References 45 publications

Emergence of distinct electronic states in epitaxially-fused PbSe quantum dot superlattices

Emergence of distinct electronic states in epitaxially-fused PbSe quantum dot superlattices

Electronic properties of atomically coherent square PbSe nanocrystal superlattice resolved by Scanning Tunneling Spectroscopy

Emergence of Distinct Electronic States in Epitaxially-Fused PbSe Quantum Dot Superlattices

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