PbS Quantum Dots - fluorescence λem 850 nm,stabilized with octadecylamine ligands

Cat. No.: P140910

GRADE & PURITY fluorescence λem 850 nm,stabilized with octadecylamine ligands

Storage

Store at 2-8°C

Shipped In

Wet ice

Overview

PbS QDs have large Bohr radius with strong quantum effect. Due to its excellent nonlinear optical property, suitable forbidden band width, electronic energy band across 900~1600 nm infrared wavelength range that overlap with “communication wavelength”, PbS QDs have the potential to be used in optoelectronic devices, communication devices, light-emitting diodes, solar cells, and other fields. In addition, PbS QDs can be easily transferred into water with high biocompatibility, thus can be widely used for bio-imaging and–labeling applications. Synthesized using our proprietary unique technology, our PbS QDs have narrow particle size distribution, high color purity, near-infrared emission, and excellent stability.

Specifications

Specifications & Purity

fluorescence λem 850 nm,stabilized with octadecylamine ligands

Storage

Store at 2-8°C

Shipped In

Wet ice

This product requires cold chain shipping. Ground and other economy services are not available.

Chemical and Physical Properties

• Sensitivity: Light sensitive

Application Protocols

Item-specific tested applications and detailed protocols are not provided; refer to CoA/Spec Sheet. The following general, non-binding protocols are commonly used for PbS QDs.

• Preparing a filtered dispersion for optics:
  1. Warm the sealed vial to room temperature. 2) Vortex gently and sonicate (bath, ≤5 min) if needed. 3) Dilute in dry toluene or solvent compatible with the ligand shell. 4) Filter through 0.2 µm PTFE into an amber vial. 5) Record absorption/PL.
• Spin-coating a QD film (layer-by-layer halide exchange):
  1. Dispense QD ink (10–20 mg/mL in toluene). 2) Spin 2000 rpm, 40 s. 3) Immediately drop-cast PbI2 in DMF (0.01–0.05 M) for 10–20 s. 4) Spin-rinse with acetonitrile. 5) Repeat 4–8 cycles to target thickness. 6) Anneal 90°C, 10 min under N2.
• Solution-phase ligand exchange (short thiol example):
  1. In N2 glovebox, mix QD dispersion in toluene with equal volume of acetonitrile containing 20–100 mM short thiol (e.g., ethanedithiol). 2) Stir 1–10 min; monitor color/PL. 3) Precipitate with ethanol/acetone; centrifuge. 4) Redisperse in DMF/DMSO. 5) Iterate to reach desired solubility.
• Aqueous transfer (if bio-capable shells are used):
  • Exchange with amphiphilic polymers or zwitterionic ligands; dialyze to remove excess small molecules; maintain low ionic strength to prevent aggregation.

Biological Roles

• Intrinsic biological role: None. PbS Quantum Dots are synthetic inorganic nanocrystals without a natural metabolic function.
• Research use in bio-related studies (general, not clinical):
  • NIR/SWIR fluorescent labels: When suitably surface-modified (e.g., amphiphilic polymer or PEG shells), PbS QDs can serve as high-contrast labels in complex media, benefiting from reduced autofluorescence in the NIR.
  • Sensing platforms: Surface-bound recognition elements (peptides, aptamers) coupled to QDs enable optical readouts via PL intensity or lifetime changes.
  • Energy transfer probes: Tunable donors/acceptors for FRET beyond 800 nm using organic dyes or other QDs.
• Considerations for biological media:
  • Maintain colloidal stability in buffers with controlled ionic strength; multivalent ions and proteins can bridge/aggregate particles.
  • Robust passivation (e.g., compact inorganic shells or crosslinked polymers) reduces ligand desorption and ion leakage that could affect cells or enzymes in vitro.
  • Photostability vs. photobrightening/darkening must be characterized under experimental illumination.
• Safety note: Lead content and nanoparticle nature warrant strict containment and disposal practices. These materials are for research use only and are not intended for diagnostic, therapeutic, or in vivo use.
• Item-specific bioconjugation handles and endotoxin status: Not specified for this item; refer to CoA/Spec Sheet.

Buffer Applications

PbS Quantum Dots are not classical buffering agents. However, buffers can be relevant for aqueous dispersions and bioassays.

• Applicability: Only if the QDs are supplied or converted to water-dispersible colloids. Item-specific water compatibility: Not specified for this item; refer to CoA/Spec Sheet.
• General guidance for aqueous work:
  • Use low- to moderate-ionic-strength buffers (e.g., 1–10 mM HEPES, PBS ≤0.5×) to reduce screening-induced aggregation; avoid divalent cations (Ca2+, Mg2+) unless required and tested.
  • Maintain pH where ligand shells are stable (carboxylate shells: pH 7.4–8.2; amine/PEG shells tolerate wider ranges). Extreme pH can strip ligands and quench PL.
  • Add small amounts of nonionic surfactants (e.g., 0.01–0.05% Tween-20) if compatible to mitigate nonspecific adsorption.
• Filtration and sterilization:
  • Sterile filtration through 0.22 µm can remove dust/aggregates but may reduce concentration via membrane adsorption; pre-condition filters with buffer containing 0.01% surfactant when compatible.
• Storage in buffers: Prefer refrigerated, dark storage; avoid freeze-thaw. Monitor hydrodynamic size (DLS) and PL over time to assess stability.

Green Alternatives

PbS QDs provide unique NIR–SWIR performance but contain lead and often use chlorinated/nonpolar solvents. Consider alternatives when toxicity or regulatory constraints dominate.

• Potential alternatives (literature/general):
  • Ag2S QDs: Lead-free SWIR emission; typically lower absorption cross-section and PLQY but improved biocompatibility profile.
  • CuInS2 (CIS) or AgInS2 (AIS) QDs: Broad NIR emission; cadmium/lead-free; wider emission and lower mobility vs PbS.
  • InP-based QDs: Visible–NIR; limited reach into deep SWIR but lower toxicity than lead salts.
  • Perovskite QDs (CsPbX3): High PLQY; still lead-containing and moisture-sensitive; less suitable for SWIR.
• Process/solvent greening:
  • Replace toluene/chloroform with toluene/anisole/2-MeTHF where compatible with ligands.
  • Use greener antisolvents (isopropanol/ethanol) cautiously to avoid ligand stripping.
  • Explore aqueous-phase ligand shells (PEGylated, zwitterionic) to enable water processing for certain applications.
• Trade-offs:
  • Lead-free systems generally show reduced carrier mobilities or broader emission; PbS remains advantageous for SWIR photodetection and broadband absorption.
  • Greener solvents can alter film morphology and surface chemistry; re-optimize spin speeds, concentrations, and drying ramps.
• Recommendation: If regulatory or EHS priorities preclude lead, benchmark Ag2S or CIS QDs under identical optical and device tests to quantify performance gaps.

Pharmaceutical Uses

This product is a research-grade nanomaterial and is not intended for pharmaceutical, clinical, or in vivo applications.

• Regulatory/compendial status: Not applicable; no pharmacopeial monograph for PbS Quantum Dots.
• Potential roles in pharmaceutical R&D (research-only, general):
  • Analytical tracers for imaging assay development or device calibration in the NIR–SWIR range.
  • Model nanocarriers in formulation science to study colloidal stability, ligand exchange, and protein corona effects (in vitro only).
• Manufacturing/process considerations (general):
  • Solvent residuals, free ligand content, and metal ion leachables require stringent control for any process development experiments; evaluate via GC, ICP-MS, and XPS.
  • Surface functionalization reproducibility is critical for batch-to-batch consistency; track via TGA (ligand loading) and FTIR/NMR (ligand identity).
• Important disclaimer: No therapeutic claims are made. Not for human or animal use. For research use only, as stated in Product Data.

Physical Properties

• Appearance: Not specified for this item; refer to CoA/Spec Sheet.
• Grade/Purity: Not specified for this item; refer to CoA/Spec Sheet.
• Optical features (literature/general for PbS QDs):
  • Bandgap: Bulk PbS Eg ≈ 0.37 eV at 300 K; quantum confinement increases Eg with decreasing size, enabling absorption/emission from ~800 nm to >2000 nm (NIR–SWIR). Specific peak positions for this item: Not specified for this item; refer to CoA/Spec Sheet.
  • Photoluminescence quantum yield (PLQY): Highly synthesis- and surface-dependent; typical ranges 5–60% (literature). Item-specific PLQY: Not specified for this item; refer to CoA/Spec Sheet.
• Size/dispersion (item-specific): Core diameter, PDI, and dispersing solvent: Not specified for this item; refer to CoA/Spec Sheet.
• Density (bulk, literature): ~7.6 g/cm³ for crystalline PbS (nanocrystal effective density depends on ligand shell/solvent and is not typically reported as a spec).
• Melting point/boiling point: Not applicable for colloids; bulk PbS mp ~1118 °C (literature). QDs decompose/sinter before bulk melting.
• Solubility/miscibility (general): Determined by surface ligands. Oleate-capped PbS is soluble in nonpolar solvents (hexane, toluene, chloroform). Halide/short-ligand–exchanged PbS disperses in polar solvents (DMF, DMSO, acetonitrile, water with appropriate shells). Exact solvent compatibility for this item: Not specified for this item; refer to CoA/Spec Sheet.
• Refractive index (bulk, literature): n ≈ 4–5 (mid-IR; strongly wavelength dependent).

Quality & Grades

• Item-specific grade/purity and ligand system: Not specified for this item; refer to CoA/Spec Sheet.
• How QD quality is typically defined (general):
  • Size and distribution: Mean core diameter (TEM), polydispersity (σ or PDI), and crystalline phase (XRD).
  • Optoelectronic metrics: First exciton absorption peak and FWHM, photoluminescence (PL) peak/FWHM, PL quantum yield, lifetime, and trap density (TA/PL decay).
  • Surface chemistry: Ligand identity/density (oleate, halide, amines, short thiols), inorganic shells or passivation layers; residual precursors (Pb-oleate, silyl sulfide) and free ligand.
  • Chemical cleanliness: Low levels of oxide/sulfate on surfaces (XPS), minimal adventitious carbon/halogen, and controlled halide content if used.
  • Process compatibility: Solvent system, concentration (mg/mL), and filtration level (0.2 µm recommended for film casting/spin-coating).
• Interpreting common labels (general):
  • “Photonic/optical grade” emphasizes narrow FWHM, stable emission, low scattering.
  • “Electronic grade” emphasizes ligand exchange compatibility, low trap density, and reproducible film formation.
  • “Biofunctional grade” emphasizes water dispersibility, low endotoxin/bioburden, and functional handles (–COOH/–NH2/–PEG) for research labeling.
• Recommendation: Review the item’s CoA for exact band-edge position(s), PLQY, ligand identity, solvent, solids content, and any stabilizers prior to use.

Reaction & Applications

This material functions as a size-tunable NIR–SWIR semiconductor rather than a classical molecular reagent. Key research applications include:

• Optoelectronics and photonics (general):
  • Photodetectors and imaging arrays: PbS QDs enable solution-processed NIR/SWIR detection with tunable cut-on wavelengths via core size control.
  • Photovoltaics and photothermal conversion: Multiple exciton generation (MEG) and broadband absorption have been explored in research cells; ligand engineering improves transport.
  • Light-emitting and optical tags: NIR emission for labels, beacons, and optical communications components; stability depends on surface passivation.
• Chemical/photochemical roles (general):
  • Sensitizers in photocatalysis: QD-sensitized processes for H2 evolution or CO2 reduction under IR-visible light have been reported; surface redox couples and sacrificial donors acceptors must be tuned.
  • Energy transfer platforms: Size-tuned donors/acceptors for FRET in the NIR; requires rigorous control of interparticle distance via ligands/spacers.
• Device/process integration tips:
  • Perform ligand exchanges (e.g., with halides, short thiols, metal chalcogenide complexes) to increase film conductivity; carefully rinse to remove excess ions.
  • Control atmosphere (dry N2) during film formation to reduce oxidation and preserve PL/electrical properties.
  • Post-deposition treatments (mild anneal 60–120°C, brief UV–ozone to clean surfaces) can improve uniformity; excessive heat or oxidation degrades QDs.
• Item-specific “Manufacturer Applications”: Not specified for this item; refer to CoA/Spec Sheet.

Reaction Conditions

Conventional stoichiometric reaction conditions are not directly applicable. Below are general processing/conditioning parameters from the literature for PbS QDs.

• Film formation (general):
  • Spin coating: 1000–3000 rpm for 30–60 s from toluene/chlorobenzene dispersions (5–30 mg/mL), giving 20–150 nm layers; filter through 0.2 µm.
  • Annealing: 60–120°C for 5–30 min under N2 to remove residual solvent; avoid >150°C to prevent sintering/oxidation unless dense films are desired.
• Ligand exchange (general):
  • Solid-state halide exchange: Brief exposure (10–60 s) to solutions of PbI2/PbBr2 in DMF/DMSO during layer-by-layer deposition; rinse with acetonitrile.
  • Solution-phase short-ligand exchange: Treat nonpolar dispersions with stoichiometric thiols/halides/ammonium halides; monitor PL and DLS; quench and purify by antisolvent precipitation.
• Optical/electrical characterization:
  • UV–vis–NIR: Track first exciton peak shift to monitor size and surface changes.
  • PL/QY: Excite in the visible/NIR; integrate sphere recommended for QY.
  • Conductivity/mobility: Two-point or OFET structures under inert atmosphere; encapsulate to mitigate O2 sensitivity.
• Storage/handling during processing:
  • Work under dry N2 or Ar. Protect films and dispersions from intense UV/ozone. Use freshly prepared exchanges to limit hydrolysis of reagents (e.g., PbX2–DMF complexes).
• Expected outcomes (literature): Improved charge transport after halide/short-ligand exchange, with some PL quenching relative to long-chain–capped colloids.

Safety & Handling

• GHS classification, signal word, pictograms, H-statements: Not specified for this item; refer to SDS.
• Key hazards (general/literature):
  • Lead-containing nanomaterial: Lead compounds are toxic; avoid ingestion, inhalation, and skin contact. Nanoparticles may present additional inhalation and environmental hazards.
  • Solvent hazards: Dispersions often contain flammable/toxic organic solvents (e.g., toluene, chloroform). Manage per solvent SDS.
• PPE and engineering controls (best practice):
  • Use in a chemical fume hood or enclosure; avoid aerosolization. Wear lab coat, safety glasses, and appropriate chemically resistant gloves (e.g., nitrile; double-glove for chlorinated solvents). Consider P100 particulate protection if handling dry powders.
• Storage guidance: Store at 2–8°C (per Product Data). Protect from light to minimize photo-oxidation. Keep container tightly closed; avoid prolonged exposure to air/moisture that can oxidize the QD surface and reduce PL.
• Incompatibilities (general): Strong oxidizers; acids/bases that strip ligands; halogenating agents; sulfur scavengers; chelators that can displace surface ligands; ozone/UV.
• First-aid overview (consult SDS for details):
  • Inhalation: Move to fresh air; seek medical advice.
  • Skin/eye contact: Rinse with water for ≥15 min; remove contaminated clothing; seek medical advice.
  • Ingestion: Rinse mouth; do not induce vomiting; seek medical attention.
• Waste disposal: Collect as hazardous waste under local regulations for lead-containing materials and organic solvents; prevent environmental release.

Solvent Selection

Solvent choice for PbS Quantum Dots is governed by surface ligands and intended processing.

• Item-specific solvent system: Not specified for this item; refer to CoA/Spec Sheet.
• General guidance by ligand class:
  • Long-chain carboxylates (e.g., oleate): Good solubility in nonpolar media (hexane, toluene, cyclohexane, chloroform). Toluene and chlorobenzene provide slower evaporation for uniform films; hexane enables rapid precipitation/antisolvent steps.
  • Halide/short-ligand–exchanged QDs (e.g., PbX2, thiols, amines): Disperse in mid- to polar solvents (chloroform, acetonitrile, DMF, DMSO, NMP). For solid-state devices, DMF/DMSO facilitate layer-by-layer ligand exchange.
  • Water-dispersible (amphiphilic polymer or zwitterionic shells): Buffer- and electrolyte-sensitive; use low-ionic-strength aqueous media, adjust pH to maintain colloidal stability.
• Practical tips:
  • Filter dispersions (0.2 µm PTFE or PVDF) before spin/dip coating to remove dust/aggregates.
  • Avoid alcohols as primary solvents for oleate-capped dots (can induce partial ligand stripping); small fractions can be used as antisolvents.
  • Match vapor pressure to coating method: high vp (hexane) for fast drying; moderate vp (toluene) for better film uniformity; low vp (chlorobenzene) for thicker films.
• Comparison (general):
  • Nonpolar (toluene): high optical quality films, slower drying.
  • Polar aprotic (DMF/DMSO): enables ionic/short-ligand exchanges, but can quench PL without passivation.
  • Water: only for purpose-built hydrophilic shells; screen ionic strength carefully.

Storage & Reconstitution

• Storage conditions (item-specific): Store at 2–8°C (per Product Data). Ship on wet ice. Keep tightly sealed in the dark to minimize photo-oxidation and solvent loss.
• Stability notes (general): QD optical properties degrade with oxygen, moisture, and light. Minimize headspace oxygen and avoid repeated warming/cooling cycles. Do not freeze standard organic dispersions; freezing can cause phase separation and aggregation.
• Reconstitution/redispersion (general):
  • If supplied as a concentrated dispersion: Bring to room temperature, vortex gently, and, if necessary, sonicate in a room-temperature bath ≤5 min to break soft aggregates. Avoid probe sonication that can strip ligands.
  • If supplied as a dry solid (not typical; item-specific form not specified): Wet with a few drops of compatible anhydrous solvent (e.g., toluene for oleate-capped dots), then dilute to target concentration while gently swirling. Allow 10–30 min for full solvation.
• Handling tips:
  • Work under inert atmosphere for extended manipulations. Use amber vials with PTFE-lined caps. Pre-filter before device fabrication or optical measurements.
  • Record initial absorption/PL after receipt; track changes over time to assess shelf-life.
• Item-specific concentration, solvent of supply, ligand identity, and recommended shelf-life: Not specified for this item; refer to CoA/Spec Sheet.
• Research Use Note: For research use only.

Structure & Identity

PbS Quantum Dots are nanocrystalline lead(II) sulfide with size-dependent electronic and optical properties arising from quantum confinement.

• Item-specific identifiers (CAS, InChIKey, SMILES): Not specified for this item; refer to CoA/Spec Sheet.
• Molecular formula (literature): PbS (rocksalt structure; 1:1 stoichiometry of Pb2+ and S2− in the bulk crystal lattice).
• Molecular weight (formula unit, literature): 239.27 g/mol for PbS (note: nanoparticles are multi-thousand–to–multi-million formula units; “molecular weight” of a particle depends on size/distribution).
• Structural features (literature/general):
  • Crystal structure: Face-centered cubic (NaCl/rocksalt, space group Fm-3m) with alternating Pb and S ions.
  • Nanoparticle morphology: Commonly quasi-spherical; cubes or other facets possible depending on ligands/conditions. Size typically 2–10 nm for NIR-emissive dots; exact size for this item: Not specified for this item; refer to CoA/Spec Sheet.
  • Surface chemistry: Capped by organic ligands (e.g., oleate, amines, halides) to control growth, passivate traps, and impart solubility; exact ligand set for this item: Not specified for this item; refer to CoA/Spec Sheet.
• 2D description in words (general): A nearly spherical nanocrystal composed of a cubic PbS lattice; the surface is terminated by coordinating ligands that bind to Pb- or S-terminated facets, yielding a colloidally stable particle with a quantum-confined core.

Synthetic Utility

While not a molecular building block, PbS Quantum Dots offer utility as functional nanomaterials within synthetic and materials chemistry workflows.

• As-prepared colloids (general):
  • Ligand platform: Long-chain carboxylates/amines enable post-synthetic ligand exchange with short ligands (thiols, halides, metal chalcogenide complexes) to tailor interparticle coupling and film conductivity.
  • Heterostructures: Serve as cores for overcoating (e.g., CdS-, ZnS-, or metal chalcogenide shells) to modulate band offsets, passivate traps, and shift emission.
• As reactive scaffolds:
  • Surface-initiated chemistries: EDC/NHS coupling on carboxylate shells; thiol–ene and click reactions on functional ligands; halide-assisted exchanges to introduce inorganic passivation (PbX2).
  • Catalytic motifs: QD surfaces act as photoredox centers under NIR illumination to generate radicals or activate substrates; kinetics depend on trap density and ligand permeability.
• Retrosynthetic/materials design role:
  • Tailor the first exciton energy via core size to match donor/acceptor levels in multilayer devices.
  • Utilize ligand length and dipole to engineer band alignment and vacuum level shifts at interfaces.
• Practical notes:
  • Purification via precipitation–redispersion (e.g., MeOH/IPA/acetone as antisolvents) removes excess ligands but can etch surfaces; optimize ratios/time.
  • Minimize oxygen and moisture during exchanges to suppress oxidation (PbS→PbSOx) and preserve PL/electrical performance.

Target Specificity

Not applicable. This product is a semiconductor nanomaterial, not an affinity reagent. No antigen/epitope/clone/isotype information is relevant. For optical targeting in research, specificity arises from user-applied surface functionalization, which is not specified for this item; refer to CoA/Spec Sheet.