Monodisperse, Air-Stable PbS Nanocrystals <i>via</i> Precursor Stoichiometry Control

Weidman, Mark C.; Beck, Megan E.; Hoffman, Rachel S.; Prins, Ferry; Tisdale, William A.

doi:10.1021/nn5018654

Cited by 352 publications

(506 citation statements)

References 43 publications

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“…84 The choice of synthesis route may also limit the obtainable range of NC sizes, though one step procedures yeilding NCs from 3 nm to 10 nm 4 exhibiting air stable properties for upto several months have been reported. 7 Solid-state ligand exchange processes can be employed to improve the mobility of charge carriers in the film, however such a process may result in incomplete ligand exchange and introduce traps. Indeed, such a process is an effective way to intentionally introduce sensitizing centers in order to promote gain in photoconductors, 23 though such centers are detrimental to realising high efficiency high speed photodiodes.…”

Section: Discussionmentioning

confidence: 99%

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Lead sulphide nanocrystal photodetector technologies

2016

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2 Few other areas of study have uncovered the secrets of the universe like that of the interaction between light and matter, leading to many revolutionary scientific discoveries. The interaction of light, in particular with semiconducting materials, has enabled us to understand the behaviour of various fundamental phenomena and has laid the foundation of the optoelectronic systems that we rely on today. The majority of such systems necessitate the detection of light which is achieved via the use of photodetector devices. A photodetector converts incident photons into an electrical signal, which in the solid-state, is assembled together with an application-oriented readout integrated circuit (ROIC). Present-day commercially available photodetectors are typically made from gallium phosphide/silicon carbide (GaP)/(SiC), silicon (Si) and indium gallium arsenide/germanium (InGaAs)/(Ge) for detection in the ultraviolet (UV), visible and near-infrared (IR) regimes of the electromagnetic spectrum, respectively. For mid and far IR, lead sulphide (PbS), lead selenide (PbSe), indium antimonide (InSb), indium arsenide (InAs) and mercury cadmium telluride (HgCdTe) based photodetectors are commonly used. Photodetectors based on a photoemissive principle such as photomultiplier tubes (PMTs) are also widely used for ultrasensitive detection in the UV to near-IR spectral regime and are fabricated using alkali metals having a low workfunction. For applications demanding multispectral detection, 'two-colour' detectors are often manufactured with a bi-level structure, for example consisting of an IR transmitting Si photodiode mounted over an IR sensitive PbS photoconductor. Such a device structure has drawbacks that include added cost, increased complexity of device fabrication and associated issues in implementation. Furthermore, a significant majority of applications are based upon UV to near-IR light detection where the indirect bandgap of Si, the InGaAs epitaxial growth process, PMT bulkiness and high bias voltage requirement all present challenges and renders their use with flexible platforms impossible. As a result significant research effort continues to be expended on the development of a singlesystem multispectral photodetector to replace two or more detectors. In the last decade amongst all the candidate materials studied 1 PbS semiconductor nanocrystals (NCs), often referred as 'quantum dots', have emerged as the most promising material for the fabrication of 3 this type of photodetector. Such has been the progress in their development that reported PbS NC based photodetectors have already outperformed conventional state-of-the-art photodetectors in many aspects including low-cost room temperature device fabrication via solution processing, flexible substrate compatibility, broadband spectral sensitivity along with the figures of merit achieved, Fig 1a. In this review article, we present an overview of recent developments in PbS NC based photodetectors. We first provide a brief introduction to PbS NCs and their releva...

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Section: Discussionmentioning

confidence: 99%

“…1c,d. 7 The use of surfactant molecules bound to the PbS NC surface, such as oleic acid, enables their dispersion in a variety of solvents and prevents NC aggregation. PbS NCs have well-defined (111) and (001) …”

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Lead sulphide nanocrystal photodetector technologies

2016

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“…These shifts are comparable to previouslyreported values for PbS CQDs with this bandgap. 20 The absorption and PL in the film (Figure 2(b)) are red-shifted by approximately 60 nm, which suggests electronic coupling among the CQDs in the solid state. X-ray photoelectron spectroscopy (XPS, PHI-5500) reveals a strong signature for iodide, suggesting good incorporation of iodide into the final film (Figure 2(c)).…”

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Single-step colloidal quantum dot films for infrared solar harvesting

Kiani

Sutherland

Kim

et al. 2016

Applied Physics Letters

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“…DTCP was synthesized in five steps from 2-Methylthiophene following Lucas et al and 7.5 nm oleic acid-capped PbS QDs were obtained according to Weidman et al [12,13]. All materials were processed and characterized under inert conditions in a glovebox.…”

Section: Methodsmentioning

confidence: 99%

Towards Photo-Switchable Transport in Quantum Dot Solids

Schedel

Thalwitzer

Khoshkhoo

et al. 2016

Zeitschrift Für Physikalische Chemie

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Abstract:We use the photochromic organic semiconductor 1,2-Bis(5′-carboxy-2′-methylthien-3′-yl)-cyclopentene (DTCP) to cross-link PbS quantum dots assembled into thin films. The ligand exchange is monitored by means of vibrational spectroscopy (FT-IR) and core-level X-ray photoemission spectroscopy (XPS). Transport measurements in a field-effect transistor (FET) set-up reveal ambipolar behavior with hole and electron mobilities on the order of 10 −4 cm 2 /Vs and 10 −5 cm 2 /Vs, respectively. Exposure to UV light from a 4 W UV lamp does not significantly change the transport properties, indicating that switching of DTCP is hindered in the hybrid film. We find a pronounced photo-conductance with rapid and reversible photo-response on the order of few seconds, which we attribute to (de-)filling of QD trap states. Our results indicate that hybrid, nanostructured networks of PbS QDs cross-linked with DTCP can be obtained by the presented procedure but that switching of the QD-bound DTCP appears to be hindered compared to the pure, unbound molecular species. We discuss future means to address this problem.

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Monodisperse, Air-Stable PbS Nanocrystals via Precursor Stoichiometry Control

Cited by 352 publications

References 43 publications

Lead sulphide nanocrystal photodetector technologies

Lead sulphide nanocrystal photodetector technologies

Single-step colloidal quantum dot films for infrared solar harvesting

Towards Photo-Switchable Transport in Quantum Dot Solids

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