Controlled Chemical Doping of Semiconductor Nanocrystals Using Redox Buffers

Engel, Jesse; Surendranath, Yogesh; Alivisatos, A. Paul

doi:10.1021/ja305293e

Cited by 42 publications

(48 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the contrary, in the subsequent anodic scan to + 2 V, clear oxidation processes can be recorded in the voltammogram for all samples. These results are in agreement with an unfavorable cathodic reduction and a favorable anodic oxidation of CdSe at room temperature [41][42][43]. A second cathodic scan to − 2 V after previous oxidation is characterized by a reduction peak centered at − 1.4 V. In all cases, since the reduction peaks are only recorded upon previous anodic oxidation the potential difference between the anodic and cathodic responses cannot be assigned to the energetic positions of valence and conduction bands.…”

Section: Electrochemical Studies Of Rod-like and Pyramidal Ncssupporting

confidence: 83%

The Role of Halogens in the Synthesis of Semiconductor Nanocrystals

Juárez¹

2014

Zeitschrift Für Physikalische Chemie

View full text Add to dashboard Cite

Abstract:The presence of halogen compounds in the synthesis of semiconductor nanocrystals (NCs) produced by hot injection drastically influence their capping ligand sphere and/or chemical reactivity, allowing for the growth of hybrid systems, including composites combining NCs decorating carbon sp 2 surfaces. As a result, the presence of halide anions on the surface of some NCs has proven to have a positive impact on the optical and electrical properties. In this work the effects that halogen co-solvents (including alkylchlorides, bromides, and iodides) induce in the synthesis of rod-like Wurtzite CdSe NCs generated by hot-injection will be reviewed. The proposed mechanism of the reaction as well as a detailed characterization of the capping ligand sphere by Nuclear Magnetic Resonance (NMR) and X-Ray photoelectron Spectroscopy (XPS) will be discussed. Correlated cyclic voltammetry (CV) and XPS studies have been performed to address the effect of the halide anions on the NCs surface. Finally an example of the effect of the addition of chlorine-containing co-solvents on the synthesis of PbS rock-salt NCs will be shown.

show abstract

Section: Electrochemical Studies Of Rod-like and Pyramidal Ncssupporting

confidence: 83%

The Role of Halogens in the Synthesis of Semiconductor Nanocrystals

Juárez¹

2014

Zeitschrift Für Physikalische Chemie

View full text Add to dashboard Cite

show abstract

“…In solar cells, these materials have recently exceeded 7% certified power conversion efficiency (PCE) 5,12,13 , offering a promising path towards efficient, low-cost and roll-to-roll processed photovoltaics (PVs). Recent efforts have concentrated on eliminating trap states detrimental to carrier lifetime 5,14,15 , investigating the impact of size polydispersity on an ensemble of CQDs 16,17 , improving charge collection 13,18,19 , characterizing field-effect mobility in these materials [20][21][22][23] and developing novel doping strategies to enable new high-efficiency device architectures 6,[24][25][26] . However, present-day devices still suffer from current densities and fill factors that are well below their theoretical potential.…”

mentioning

confidence: 99%

Engineering colloidal quantum dot solids within and beyond the mobility-invariant regime

et al. 2014

View full text Add to dashboard Cite

Colloidal quantum dots are attractive materials for efficient, low-cost and facile implementation of solution-processed optoelectronic devices. Despite impressive mobilities (1-30 cm 2 V À 1 s À 1 ) reported for new classes of quantum dot solids, it is-surprisingly-the much lower-mobility (10 À 3 -10 À 2 cm 2 V À 1 s À 1 ) solids that have produced the best photovoltaic performance. Here we show that it is not mobility, but instead the average spacing among recombination centres that governs the diffusion length of charges in today's quantum dot solids. In this regime, colloidal quantum dot films do not benefit from further improvements in charge carrier mobility. We develop a device model that accurately predicts the thickness dependence and diffusion length dependence of devices. Direct diffusion length measurements suggest the solid-state ligand exchange procedure as a potential origin of the detrimental recombination centres. We then present a novel avenue for in-solution passivation with tightly bound chlorothiols that retain passivation from solution to film, achieving an 8.5% power conversion efficiency.

show abstract

“…Increasingly, focus is shifting to realizing and exploiting electronic doping in these materials, particularly in infrared NCs, like the lead chalcogenides, which are of direct importance for solar cells. Reported approaches to NC-doping have utilized incorporation of metal ions4, chemical treatments56, or electrochemical charge injection7, but “heavy doping” of lead chalcogenide NCs (persistent introduction of multiple charges into the quantum-confined band-edge states) still represents a significant challenge.…”

mentioning

confidence: 99%

Heavily doped n-type PbSe and PbS nanocrystals using ground-state charge transfer from cobaltocene

Koh

Koposov

Stewart

et al. 2013

Sci Rep

120

196

View full text Add to dashboard Cite

Colloidal nanocrystals (NCs) of lead chalcogenides are a promising class of tunable infrared materials for applications in devices such as photodetectors and solar cells. Such devices typically employ electronic materials in which charge carrier concentrations are manipulated through “doping;” however, persistent electronic doping of these NCs remains a challenge. Here, we demonstrate that heavily doped n-type PbSe and PbS NCs can be realized utilizing ground-state electron transfer from cobaltocene. This allows injecting up to eight electrons per NC into the band-edge state and maintaining the doping level for at least a month at room temperature. Doping is confirmed by inter- and intra-band optical absorption, as well as by carrier dynamics. Finally, FET measurements of doped NC films and the demonstration of a p-n diode provide additional evidence that the developed doping procedure allows for persistent incorporation of electrons into the quantum-confined NC states.

show abstract

Controlled Chemical Doping of Semiconductor Nanocrystals Using Redox Buffers

Cited by 42 publications

References 30 publications

The Role of Halogens in the Synthesis of Semiconductor Nanocrystals

The Role of Halogens in the Synthesis of Semiconductor Nanocrystals

Engineering colloidal quantum dot solids within and beyond the mobility-invariant regime

Heavily doped n-type PbSe and PbS nanocrystals using ground-state charge transfer from cobaltocene

Contact Info

Product

Resources

About