Investigating the Phosphine Chemistry of Se Precursors for the Synthesis of PbSe Nanorods

Koh, Weon-kyu; Yoon, Yong Tae; Murray, Christopher B.

doi:10.1021/cm1033172

Cited by 41 publications

(54 citation statements)

References 21 publications

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“…This is similar to the results obtained when no water is added which indicates that diethylamine is not responsible for the aspect ratio and yield changes. This result is contrary to that found by Koh et al 14 who suggest that diethylamine increases the nanorod reaction rate.…”

Section: Scheme 1 Reaction Of Compound 1 With Water To Yield 2 and Dcontrasting

confidence: 99%

“…This reaction suggests that it is possible that water is acting indirectly by creating 2 and diethylamine, and one or both of these hydrolysis products are responsible for the nanorod aspect ratio and yield modifications. Koh et al 14 have also proposed that diethylamine is present in the nanorod reaction, however they suggest that is comes from the decomposition of 1 at elevated temperatures.…”

Section: Resultsmentioning

confidence: 99%

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Control of PbSe Nanorod Aspect Ratio by Limiting Phosphine Hydrolysis

et al. 2013

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The aspect ratio and yield of PbSe nanorods synthesized by the reaction of Pb-oleate with tris(diethylamino)phosphine selenide are highly sensitive to the presence of water, making it critical to control the amount of water present in the reaction. By carefully drying the reaction precursors and then intentionally adding water back into the reaction, the nanorod aspect ratio can be controlled from 1.1 to 10 and the yield from 1 to 14% by varying the water concentration from 0 to 204 mM. (31)P{(1)H} and (1)H NMR show that water reacts with tris(diethylamino)phosphine to create bis(diethylamido)phosphorous acid. It was determined that bis(diethylamido)phosphorous acid is responsible for the observed aspect ratio and yield changes. Finally, it was found that excess oleic acid in the reaction can also react with tris(diethylamino)phosphine to create bis(diethylamido)phosphorous acid, and upon the removal of both excess oleic acid and water, highly uniform, nonbranching nanorods were formed.

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Section: Scheme 1 Reaction Of Compound 1 With Water To Yield 2 and Dcontrasting

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Control of PbSe Nanorod Aspect Ratio by Limiting Phosphine Hydrolysis

et al. 2013

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“…The PdSe bond in HPTSe is also very strong: According to XRD (Figure 5a). 28 Observed nanodot band gaps appear erratic at first glance ( Figure 6a,b); however, this is in great part due to different nanodot sizes across batches: Singlecrystalline domain sizes (diameters) obtained from XRD peak widths are all smaller than Bohr radii for CdS (<3.0 nm) and CdSe (<5.6 nm) and are thus confined (quantized) 55 (Table 3). When corrected for size, 56 CdS 1Àx Se x nanodot band gaps progressively widen (blue shift) with increasing sulfur content (Figure 6c).…”

Section: Resultsmentioning

confidence: 99%

“…Coupled thermogravimetric mass spectrometry analysis (TGA-MS) showed that HPT accelerates precursor decomposition by releasing amines. 28 Trioctyl-and tributylphosphineÀchalcogenides (TOPE and TBPE; E = S, Se, Te) react with Cd and Zn oleates or alkylphosphonates via a Lewis acid substitution mechanism, producing ME (M = Cd, Zn) nanocrystals, phosphine oxides (TOPO or TBPO), and oleic or phosphonic anhydrides. 29 Using a high-throughput synthesis platform, CdSe yield as well as nucleation and growth rates from Cd(ODPA) 2 in TOPO were found to depend on phosphine selenide concentration and number of aryl groups.…”

Section: Published Online 101021/nn301182hmentioning

confidence: 99%

Molecular Control of the Nanoscale: Effect of Phosphine–Chalcogenide Reactivity on CdS–CdSe Nanocrystal Composition and Morphology

et al. 2012

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We demonstrate molecular control of nanoscale composition, alloying, and morphology (aspect ratio) in CdS-CdSe nanocrystal dots and rods by modulating the chemical reactivity of phosphine-chalcogenide precursors. Specific molecular precursors studied were sulfides and selenides of triphenylphosphite (TPP), diphenylpropylphosphine (DPP), tributylphosphine (TBP), trioctylphosphine (TOP), and hexaethylphosphorustriamide (HPT). Computational (DFT), NMR ( 31 P and 77 Se), and high-temperature crossover studies unambiguously confirm a chemical bonding interaction between phosphorus and chalcogen atoms in all precursors. Phosphine-chalcogenide precursor reactivity increases in the order: TPPE < DPPE < TBPE < TOPE 1-x Se x quantum dots were synthesized via single injection of a R 3 PS-R 3 PSe mixture to cadmium oleate at 250 degree C. X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV/Vis and PL optical spectroscopy reveal that relative R 3 PS and R 3 PSe reactivity dictates CdS 1 -xSe x dot chalcogen content and the extent of radial alloying (alloys vs core/shells). CdS, CdSe, and CdS 1 -x Se x quantum rods were synthesized by injection of a single R 3 PE (E = S or Se) precursor or a R 3 PS-R 3 PSe mixture to cadmium-phosphonate at 320 or 250 degree C. XRD and TEM reveal that the length-to-diameter aspect ratio of CdS and CdSe nanorods is inversely proportional to R 3PE precursor reactivity. Purposely matching or mismatching R 3 PS-R 3 PSe precursor reactivity leads to CdS 1 -x Se x nanorods without or with axial composition gradients, respectively. We expect these observations will lead to scalable and highly predictable "bottom-up" programmed syntheses of finely heterostructured nanomaterials with well-defined architectures and properties that are tailored for precise applications. P reparative nanotechnology or "nanomanufacturing" is rapidly evolving toward fabrication of ever more complex materials with precise structure and properties. Tuning composition, relative configuration, and spatial arrangement of heterostructured nanomaterials can impact our ability to engineer and direct energy flows at the nanoscale. In the case of II 3 VI and IV 3 VI semiconductors, composition control has been demonstrated for homogeneously alloyed CdS 1Àx Se x , 1À4 CdS 1Àx Te x , 5 CdSe 1Àx Te x , 6 PbS x Se 1Àx , PbS x Te 1Àx , and PbSe x Te 1Àx 7 nanocrystals with size-and composition-tunable band gaps. 4,8,9 In some cases, a nonlinear relationship between composition and absorption/emission energies, called optical bowing, resulted in new properties not obtainable from the parent binary systems. 3 For example, CdS x Te 1Àx nanocrystals displayed small absorptionÀ emission spectral overlap, up to 150 nm Stokes shifts, and significantly red-shifted PL with respect to CdS and CdTe nanocrystals. 5 Controlling nanocrystal morphology is key to controlling nanocrystal properties. 10À14 A common technique to produce nanorods, for example, is to perform slow and/or subsequent reactant injections. 15À17 In i...

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“…43 Certain additives such as tris(diethylamino)phosphine accelerate PbSe growth by releasing amine in situ. 43 The concentrations of TOPSe and TOP-telluride (TOPTe) affect the composition of ternary PbSeTe alloys. 44 Relative Zn and Cd precursor concentrations 45 and reaction temperature affect the composition of Zn x Cd 1−x Se alloys.…”

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confidence: 99%

Molecular Chemistry to the Fore: New Insights into the Fascinating World of Photoactive Colloidal Semiconductor Nanocrystals

Vela

2013

J. Phys. Chem. Lett.

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Colloidal semiconductor nanocrystals possess unique properties that are unmatched by other chromophores such as organic dyes or transition-metal complexes. These versatile building blocks have generated much scientific interest and found applications in bioimaging, tracking, lighting, lasing, photovoltaics, photocatalysis, thermoelectrics, and spintronics. Despite these advances, important challenges remain, notably how to produce semiconductor nanostructures with predetermined architecture, how to produce metastable semiconductor nanostructures that are hard to isolate by conventional syntheses, and how to control the degree of surface loading or valence per nanocrystal. Molecular chemists are very familiar with these issues and can use their expertise to help solve these challenges. In this Perspective, we present our group's recent work on bottom-up molecular control of nanoscale composition and morphology, lowtemperature photochemical routes to semiconductor heterostructures and metastable phases, solar-tochemical energy conversion with semiconductor-based photocatalysts, and controlled surface modification of colloidal semiconductors that bypasses ligand exchange. KeywordsBio-imaging, Building blockes, Colloidal semiconductor nanocrystals, Conventional synthesis, liquid exchanges, low temperatures, molecular chemistry, molecular controls, nanoscale composition, organic dye, photovoltaics, semiconductor heterostructures, surface loading, thermoelectrics, transition-metal complex, photovoltaics, energy conversion, photocatalysis ABSTRACT: Colloidal semiconductor nanocrystals possess unique properties that are unmatched by other chromophores such as organic dyes or transition-metal complexes. These versatile building blocks have generated much scientific interest and found applications in bioimaging, tracking, lighting, lasing, photovoltaics, photocatalysis, thermoelectrics, and spintronics. Despite these advances, important challenges remain, notably how to produce semiconductor nanostructures with predetermined architecture, how to produce metastable semiconductor nanostructures that are hard to isolate by conventional syntheses, and how to control the degree of surface loading or valence per nanocrystal. Molecular chemists are very familiar with these issues and can use their expertise to help solve these challenges. In this Perspective, we present our group's recent work on bottom-up molecular control of nanoscale composition and morphology, low-temperature photochemical routes to semiconductor heterostructures and metastable phases, solar-to-chemical energy conversion with semiconductor-based photocatalysts, and controlled surface modification of colloidal semiconductors that bypasses ligand exchange.C olloidal semiconductor nanocrystals (quantum dots, rods,

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Investigating the Phosphine Chemistry of Se Precursors for the Synthesis of PbSe Nanorods

Cited by 41 publications

References 21 publications

Control of PbSe Nanorod Aspect Ratio by Limiting Phosphine Hydrolysis

Control of PbSe Nanorod Aspect Ratio by Limiting Phosphine Hydrolysis

Molecular Control of the Nanoscale: Effect of Phosphine–Chalcogenide Reactivity on CdS–CdSe Nanocrystal Composition and Morphology

Molecular Chemistry to the Fore: New Insights into the Fascinating World of Photoactive Colloidal Semiconductor Nanocrystals

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