Confined-but-Connected Quantum Solids via Controlled Ligand Displacement

Baumgardner, William J.; Whitham, Kevin; Hanrath, Tobias

doi:10.1021/nl401298s

Cited by 176 publications

(261 citation statements)

References 63 publications

Supporting

Mentioning

251

Contrasting

Order By: Relevance

“…Subsequent Pb enrichment of the QD surface passivated the unstable Se surface and n-doped the QD films [37]. Similar structural transformations in PbS QD thin films have been reported for S-enriched surfaces [38] or through solvent stripping of surface ligands and atoms [39,40]. Surface passivation has been shown to increase the lifetime of photogenerated carriers [27,41] and doping shifts the Fermi level closer to the conduction or valence band, allowing carriers to populate these higher densities of states, and leads to the higher carrier mobilities reported in field-effect transistor (FET) measurements [5,37].…”

Section: Se-richsupporting

confidence: 66%

The effects of inorganic surface treatments on photogenerated carrier mobility and lifetime in PbSe quantum dot thin films

et al. 2016

View full text Add to dashboard Cite

We used flash-photolysis, time-resolved microwave conductivity (TRMC) to probe the carrier mobility and lifetime in PbSe quantum dot (QD) thin films treated with solutions of the metal salts of Na 2 Se and PbCl 2 . The metal salt treatments tuned the Pb:Se stoichiometry and swept the Fermi energy throughout the QD thin film bandgap. A stoichiometric imbalance favoring excess Se heavily p-doped the QD thin film, shifted the Fermi energy toward the valence band, and yielded the highest TRMC mobility and lifetime. Introducing Pb first compensated the p-doping and shifted the Fermi level through mid-gap, decreasing the TRMC mobility. Further Pb addition created an excess of Pb, n-doped the QD thin film, moved the Fermi level to near the conduction band, and again increased the TRMC mobility. The increase in TRMC mobility as the Fermi energy was shifted toward the band edges by non-stoichiometry is consistent with the QD thin film density of states. 2 Graphical abstract Keywords Time-resolved microwave conductivity; quantum dot; doping; spectroscopy; optoelectronic; lead selenide Highlights  Na 2 Se and PbCl 2 treatments modified the surface chemistry of PbSe quantum dots  Excess Se (Pb) p-doped (n-doped) PbSe quantum dot thin films  Carrier mobility and lifetime were studied using time-resolved microwave conductivity  Mobility increased as the Fermi level approached the band edges

show abstract

Section: Se-richsupporting

confidence: 66%

The effects of inorganic surface treatments on photogenerated carrier mobility and lifetime in PbSe quantum dot thin films

et al. 2016

View full text Add to dashboard Cite

show abstract

“…PbS QDs can form a thin film and attach to the surface and edge of ZnO NWs via a repeated spin ‐ coating process (Figure 1b). However, the spatial separation induced by the long oleic acid (OA) ligand that was used to cap QDs34 probably degrade the charge transfer between QDs and NWs. Therefore, it is necessary to exchange the long ligand with short one, such as EDT, tetrabutyl ammonium iodide (TBAI) 35, 36, 37, 38.…”

Section: Resultsmentioning

confidence: 99%

An Enhanced UV–Vis–NIR an d Flexible Photodetector Based on Electrospun ZnO Nanowire Array/PbS Quantum Dots Film Heterostructure

et al. 2016

View full text Add to dashboard Cite

ZnO nanostructure‐based photodetectors have a wide applications in many aspects, however, the response range of which are mainly restricted in the UV region dictated by its bandgap. Herein, UV–vis–NIR sensitive ZnO photodetectors consisting of ZnO nanowires (NW) array/PbS quantum dots (QDs) heterostructures are fabricated through modified electrospining method and an exchanging process. Besides wider response region compared to pure ZnO NWs based photodetectors, the heterostructures based photodetectors have faster response and recovery speed in UV range. Moreover, such photodetectors demonstrate good flexibility as well, which maintain almost constant performances under extreme (up to 180°) and repeat (up to 200 cycles) bending conditions in UV–vis–NIR range. Finally, this strategy is further verified on other kinds of 1D nanowires and 0D QDs, and similar enhancement on the performance of corresponding photodetecetors can be acquired, evidencing the universality of this strategy.

show abstract

“…8 Quite similar superlattices with square nanogeometry were recently reported by another group. 9 The calculations below will show that the band structure deviates from that of genuine 2D semiconductors, and that these systems in fact correspond to a dimensionality that can gradually decrease below 2, depending on the nanogeometry. The synthesis of square superlattices comprising rock-salt PbSe NCs was accomplished through NC self-assembly and facet-specific atomic attachment.…”

Section: B Square Superlatticesmentioning

confidence: 94%

Electronic structure of atomically coherent square semiconductor superlattices with dimensionality below two

et al. 2013

View full text Add to dashboard Cite

The electronic structure of recently synthesized square superlattices with atomic coherence composed of PbSe, CdSe, or CdTe nanocrystals (NCs) attached along {100} facets is investigated using tight-binding calculations. In experimental realizations of these systems [W. H. Evers et al., Nano Lett. 13, 2317], NC facets are atomically bonded, resulting in single-crystalline sheets, which, due to their nanogeometry, have an effective dimensionality below two. We predict electronic structures composed of successive bands formed by strong coupling between the wave functions of nearest-neighbor NCs. This coupling is mainly determined by the number of atoms at the NC bonding plane. The band structures deviate markedly from that of the corresponding two-dimensional (2D) quantum well; the 2D case can be recovered, however, if the effects of the nanogeometry are gradually reduced. The width of the bands can reach hundreds of meV, ascribing highly promising transport properties to square superlattices. The band edges are located at k = 0 except for PbSe superlattices, where their position in k space surprisingly depends on the parity of the number of {100} atomic planes in the NCs. Our calculations demonstrate that semiconductors with dimensionality below two have a strong potential for (opto-)electronic, photovoltaic, and spintronic applications.

show abstract

Confined-but-Connected Quantum Solids via Controlled Ligand Displacement

Cited by 176 publications

References 63 publications

The effects of inorganic surface treatments on photogenerated carrier mobility and lifetime in PbSe quantum dot thin films

The effects of inorganic surface treatments on photogenerated carrier mobility and lifetime in PbSe quantum dot thin films

An Enhanced UV–Vis–NIR an d Flexible Photodetector Based on Electrospun ZnO Nanowire Array/PbS Quantum Dots Film Heterostructure

Electronic structure of atomically coherent square semiconductor superlattices with dimensionality below two

Contact Info

Product

Resources

About