Synthesis Of PbS Quantum Dots Research Articles

Top-Down Synthesis of N-Type PbS Quantum Dots with High Photoluminescence Quantum Yield from Microsized Pb(OH)Cl.

Synthesis of PbS quantum dots (QDs) with uniform and controllable size is of great importance in realizing functionality manipulation, as well as building advanced devices, and these QDs have been normally synthesized via "bottom-up" colloidal chemistry. However, the problems of complicated techniques and the relative high cost of the "bottom-up" methods still need to be overcome. Herein, we present a facile and cost-effective "top-down" strategy for the production of PbS QDs with controllable sizes and narrow dispersions (4.8% < σ < 7%) based on the sulfuration reaction of highly active lead oxide and oxychloride intermediates. We investigated the two-step reaction mechanism of the QD synthesis. Initially, Pb(OH)Cl undergoes a reaction with oleic acid in the presence of oleylamine as an activator, leading to the formation of active lead oxide/oxychloride intermediates. Notably, this distinctive reaction induces the creation of numerous cracks within the intermediates, thereby augmenting the active sites available for the subsequent sulfuration reactions. In that, the sulfur precursor reacts with the intermediates, resulting in the rapid generation of a substantial number of PbS fragments. Over time, these small fragments undergo "ripening" until reaching the "critical" size threshold. Different from the ones obtained by the traditional "bottom-up" method, our synthesized colloidal QDs exhibit a S-rich surface and are confirmed to be N-type. In addition, size-tunable near-infrared photoluminescence renders these QDs a promising material for various applications.

One-pot synthesis of PbS quantum dots decorated with graphene for assisting charge carriers transport in bulk heterojunction solar cells

The photocurrent of organic bulk heterojunction (BHJ) solar cells is improved by the introduction of PbS QDs decorated with graphene (G) in their photoactive layer. The insertion of PbS QDs:G is observed to improve the exciton dissociation and charge transfer paths. PbS QDs and PbS QDs:G are synthesized by the hot-injection method. The mechanism of PbS QDs formation and the role of their growth on G sheets are explained. Incorporation of PbS QDs and PbS QDs:G into the active layer of BHJ solar cells composed of poly (3-hexylthiophene-2,5-diyl) (El-Menyawy et al., 2019; El-Menyawy et al., 2019) [6,6]:-phenyl-C61-butyric acid methyl ester (P3HT:PC61BM) is found to improve their performance. The solar cells composed of pristine P3HT:PC61BM active layer are found to deliver a photoelectrical conversion efficiency (PCE) of 2.02 %. By inserting PbS QDs in the active layer, the PCE value is increased up to 2.44 %. Further increase in PCE to 3.27 % is explored by the inclusion of PbS QDs:G in the organic active layer. The ternary composites (P3HT:PbS QDs:G:PC61BM) have supreme characteristics, and are recommended for optoelectronic applications.

Size tunable and controllable synthesis of PbS quantum dots for broadband photoelectric response

PbS quantum dots (QDs) with size-dependent photoelectric characteristics and wide spectral absorption show a great potential material for preparing near-infrared photodetectors, attracting numerous studies. This paper prepared size-tunable PbS QDs with a mean size varying from 3 nm to 9 nm via a modified hot injection method. And the effects of different factors on the size of PbS QDs in the synthesis were systematically summarized. Moreover, size-dependent optoelectronic properties of PbS QDs were studied. With the increase in size, the dark current, photocurrent, and responsivity of devices show an increase, while the 3 dB bandwidth decreases. In addition, the larger the size, the wider the detection spectrum coverage, the detectivity of the corresponding absorption peak in PbS QDs is better than another size PbS QDs, but the maximum detectivity of the large size PbS QDs is lower than that of the small size PbS QDs in the near-infrared. Therefore, selecting different PbS QDs to prepare photodetector is of great significance for practical applications with different detection requirements. Significantly, these size-tunable PbS QDs photodetectors show fast response and excellent responsivity, and detectivity.

Glycol ether additives control the size of PbS nanocrystals at reaction completion

In the colloidal synthesis of PbS quantum dots, added glycol ethers variably suppress the formation of metastable cluster intermediates. This achieves control of nanocrystal size in reactions run to completion.

Self-assembled synthesis of PbS quantum dots supported on polydopamine encapsulated BiVO4 for enhanced visible-light-driven photocatalysis

Abstract A simple self-assembled method for the deposition of PbS quantum dots (PbS QDs) on the surface of polydopamine (PDA)-encapsulated BiVO4 nanoparticles is proposed to synthesize PbS@PDA/BiVO4 nanocomposite photocatalysts with the assistance of ultrasonication. In the PbS@PDA/BiVO4 nanocomposites that was designed to improve the charge separation efficiency, PDA served as a natural adhesive and a stabilizer that can help to prevent PbS quantum dots from agglomeration, and PbS quantum dots served as the multiple exciton donor. The photocatalytic degradation of glyphosate experiments indicated that PbS@PDA/BiVO4 exhibited the enhanced photocatalytic activity under visible light irradiation. As compared with that of BiVO4, PbS@BiVO4 and PDA/BiVO4, the photocatalytic activity of PbS@PDA/BiVO4 was improved by 3.03, 1.48 and 1.58 times, respectively. The enhanced activity of PbS@PDA/BiVO4 can be attributed to the rapid transport of a mass of photoelectrons generated by multiexciton generation from PbS quantum dots to the surface of BiVO4 and the enhanced charge separation efficiency of photogenerated charge carrier.

Glycerol–water mediated centrifuge controlled green synthesis of oleic acid capped PbS quantum dots for live cell imaging

Glycerol–water mediated green synthesis of PbS quantum dots (QDs) is introduced utilizing distinctive precipitation strategies for bioimaging application.

Controlled synthesis of near-infrared quantum dots for optoelectronic devices.

We designed a facile approach for the synthesis of PbS quantum dots (QDs) using thiourea and lead acetate as sources of sulfur and lead, respectively. The sizes of the PbS QDs could be systematically controlled by simply adjusting the reaction parameters. Cd post-treatment via a cation exchange method was performed to increase the stability of QDs. As a proof of concept, colloidal PbS QDs synthesized by using air-stable thiourea were employed as light harvesters for both (i) solar driven photoelectrochemical (PEC) hydrogen generation and (ii) QDs sensitized solar cells (QDSSCs). For PEC hydrogen generation, similar saturated photocurrent densities are observed by using thiourea compared to bis(trimethylsilyl) sulfide, which is air-sensitive and unstable. For QDSSCs, the devices fabricated with QDs synthesized from thiourea reveal a better performance compared to devices fabricated with QDs synthesized from traditional bis(trimethylsilyl) sulfide. Our work demonstrates that this synthetic method is a promising alternative to the existing methodologies of PbS QDs and holds great potential for future solar technologies.

Low cost and large scale synthesis of PbS quantum dots with hybrid surface passivation

A low cost and large scale synthetic approach was developed for colloidal PbS quantum dots (QDs). The heat up strategy was adapted for large scale production, thioacetamide in oleylamine (OLA) was used as the sulphur precursor for low cost and safe synthesis, and PbCl2 in OLA was used as the lead precursor for a well passivated surface. Due to the balance between the diffusion coefficient and monomer oversaturation generated by the dissolution of small particles, an optimum growth temperature exists in the new synthesis. The synthesis was easily scaled up to produce 18 g of PbS QDs from one reaction batch, with a high chemical yield of ∼80% and the as synthesized QDs exhibit a high photoluminescence quantum yield of >40% and excellent air-stability of at least 60 days, due to the Cl− and oleate co-passivation.

Characterization of PbS/PVA/GQDs nanocomposite prepared by chemical bath deposition method

This work reports synthesis of PbS quantum dots (QDs) embedded in the poly-vinyl alcohol (PVA) in the presence of graphene quantum dots (GQDs) by the low cost and simple method of chemical bath deposition. The as-synthesized products were characterized by X-ray diffraction, transmission electron microscope and optical studies; absorption and photoluminescence measurements. Results showed that in comparison with GQDs and PbS/PVA, photoluminescence intensity of PbS/PVA/GQDs was improved and this could be attributed to rigidity of the local environment, PVA passivation and energy transformation between GQDs and PbS QDs. These analyses determined good distribution of PbS QDs on GQDs planes which is promising for practical applications in nanotechnology.

Effect of Growth Temperature on Chemical Synthesis of PbS quantum dots

Effect of Growth Temperature on Chemical Synthesis of PbS quantum dots

Size Tunable near Infrared High-Quality PbS Quantum Dots

Herein, we report the synthesis of PbS Quantum Dots (QDs) with oleic acid as surfactant molecules by non coordinating solvent route. The particles are having better size tunability by varying temperature and time of reaction. These quantum dots are characterized by optical absorption, photoluminescence and transmission electron microscopy. The resulting colloids are highly stable, extremely small size, spherical in shape, monodisperse and strong band emission. The estimated particles sizes are in the range of 2 to 6 nm. The present method of synthesis of PbS quantum dots can be used to fabricate low cost electronic devices.

Ultrasound-assisted synthesis of PbS quantum dots stabilized by 1,2-benzenedimethanethiol and attachment to single-walled carbon nanotubes

Lead sulfide (PbS) quantum dots stabilized by 1,2-benzenedimethanethiol can be synthesized by mixing Pb(NO3)2 and Na2S solutions in ethanol under ultrasound irradiation. The PbS quantum dots (2.7 and 3.6nm in diameter) are characterized by their absorption and fluorescence spectra in the near infrared region and by other surface analytical techniques. With addition of single-walled carbon nanotubes (SWNT) to the system, this ultrasound-assisted procedure allows attachment of PbS nanoparticles to SWNT surface via π–π stacking, thus providing a simple one-pot method for preparation of SWNT–PbS nanoparticle composite materials. Using the ultrasound-assisted method for synthesizing silica composites containing PbS nanoparticles by a sol–gel process is also described.

Effect of ligands on the photoluminescence properties of water-soluble PbS quantum dots

In this study, we report the synthesis of PbS quantum dots (QDs) using an aqueous route with three different ligands: thioglycolic acid (TGA), 3-mercaptopropionic acid (MPA), l-Cysteine (l-Cys) as the capping molecule. Fourier transform infrared (FT-IR) spectrometry analysis demonstrates that PbS QDs are capped with these three capping ligands through the coordination. The influences of various experimental variables, on the growth rate and luminescent properties of the obtained QDs have been systematically investigated. Experimental results indicate that the capping ligands and pH value plays a crucial role in determining the growth rate and optical properties of obtained PbS QDs. Furthermore, the stability of l-Cys-capped QDs was compared with the TGA and MPA capped QDs were investigated. Experimental results indicate that the l-Cys-capped QDs show better chemical stability than those capped by TGA and MPA. The synthesized l-Cys-capped PbS QDs were characterized by high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD), the results indicate that the QDs were about 8nm in size and dispersed well with a rock salt crystalline structure.

One-pot aqueous synthesis of near infrared emitting PbS quantum dots

In this study, we report the synthesis of PbS quantum dots (QDs) using an aqueous route with l-cysteine (l-Cys) as the capping ligands. The as-prepared PbS QDs were characterized by high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD), the results indicated that the QDs were about 7nm in size and dispersed well. There was l-Cys on the surface of QDs, which was confirmed by Fourier transform infrared (FT-IR) spectrometry. Various synthesis parameters affecting on the photoluminescent (PL) properties of the PbS QDs were discussed in detail. These parameters include the reaction time, the molar ratio of l-Cys/Pb or S/Pb, pH value and different sulfur source compounds. Furthermore, we found the as-synthesized QDs were still keeping highly PL properties not only in their original solution but also in deinoized (DI) water and phosphate buffer saline (PBS) solution during the period of 30 days, which indicated that the l-Cys capped PbS QDs could be important to the application in biomedical field in the future.

Two‐Phase Approach to High‐Quality, Oil‐Soluble, Near‐Infrared‐Emitting PbS Quantum Dots by Using Various Water‐Soluble Anion Precursors

AbstractColloidal PbS quantum dots (QDs) with tunable photoemission throughout the near‐infrared (NIR) region (ca. 750–1000 nm) were synthesized by a two‐phase approach. Here, oil‐soluble lead oleate formed by a reaction of lead acetate and oleic acid (OA, the capping agent) in n‐decane at 130 °C was used as lead precursor, and water‐soluble Na2S, thioacetamide (TAA), and thiourea, each having a different reactivity, were used as sulfur sources. When an n‐decane solution of lead precursor and an aqueous solution of sulfur precursor were mixed at the appointed temperature, oil‐soluble, near‐infrared‐emitting PbS QDs were achieved. In this study, we investigated the influence of the reactivity of water‐soluble sulfur sources on the synthesis of PbS QDs. The morphology and crystal structure of the as‐prepared PbS QDs were characterized by (high‐resolution) transmission electron microscopy (TEM), selected area electron diffraction (SAED), and X‐ray diffraction (XRD).

Facile Synthesis of High‐Quality, Water‐Soluble, Near‐Infrared‐Emitting PbS Quantum Dots

AbstractPbS quantum dots (QDs) with strong near‐infrared (NIR) fluorescence have been prepared directly in aqueous solution, by using dihydrolipoic acid (DHLA) as a stabilizer. The photoluminescence (PL) emission maximum could be tuned conveniently over a wide range (from ca. 870 nm to 1010 nm) by manipulating the experimental conditions, such as the Pb/S or DHLA/Pb molar ratios. Under optimized conditions, the maximum PL quantum yield was approximately 10 %. These resultant PbS QDs were highly stable when stored in the dark at 4 °C. After one month of storage, the PL emission intensity decreased by only about 20 %, and no obvious spectral redshift was observed. We scaled up further the synthesis of PbS QDs in the lab, where the concentration of QDs was increased to 8 mM from the usual 1 mM. The experimental results from transmission electron microscopy (TEM) imaging, selected area electron diffraction (SAED), and powder X‐ray diffractometry (XRD) analyses indicated that the as‐prepared PbS QDs had an extremely small diameter (less than 4 nm) and exhibited a face‐centered cubic crystal structure. Such aqueous quantum dots are considered to have tremendous applications in biomedical imaging and the fabrication of nanoscaled devices because of their low toxicity, strong fluorescence, excellent water‐solubility, stability, and biological compatibility relative to other highly toxic thiol (3‐mercaptopropionic acid) stabilized NIR‐emitting QDs (such as CdTe, CdHgTe, HgTe). (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2009)