15347-55-4

Upstream product

• 112-80-1 cis-Octadecenoic acid 
• 4146-73-0 lead(II) trifluoroacetate 
• 301-04-2 lead acetate 
• 6080-56-4 lead(II) acetate trihydrate 

Downstream Products

• 112-79-8 Elaidic acid 

Relevant academic research and scientific papers

Use of sulfur and selenium compounds as precursors to nanostructured materials

The presently disclosed subject matter provides processes for preparing nanocrystals, including processes for preparing core-shell nanocrystals. The presently disclosed subject matter also provides sulfur and selenium compounds as precursors to nanostructured materials. The presently disclosed subject matter also provides nanocrystals having a particular particle size distribution.

Colloidal Nanocrystals as a Platform for Rapid Screening of Charge Trap Passivating Molecules for Metal Halide Perovskite Thin Films

Charge recombination at surface trap sites is a significant impediment to metal halide perovskite (MHP) thin film-based optoelectronic devices. To passivate the surface charge traps, chemical treatments with molecules that bind to the MHP thin film surfaces can be employed. However, the current approaches to test the trap passivation efficacy of molecules on thin film surface suffer from limited through-put and low statistical significance. Here, we demonstrate the use of colloidal MHP nanocrystals (NCs) as an experimental platform for high-throughput screening of charge trap passivating molecules for MHP thin films. Using CsPbX3 (X = Br, I) NCs, over 20 molecules were rapidly screened for their surface trap passivation efficacy. Our approach identified trin-butylphosphine (TBPh) as a superb charge trap passivating molecule on MHP surfaces. TBPh treatment brings the photoluminescence quantum yield of CsPbBr3 NCs to near unity and also results in superior surface trap passivation of MHP thin films, even when compared to a previously reported treatment with pyridine. Our work highlights the benefits of utilizing the high surface area-to-volume ratio of NCs for the accelerated study of surface trap passivation using molecular treatment and then translating the findings to bulk semiconductors. This approach is broadly applicable to a wide range of semiconductors as long as they can be synthesized into NCs.

Exchange equilibria of carboxylate-terminated ligands at PbS nanocrystal surfaces

Ligand exchange reactions are commonly used to alter the surface chemistry of metal chalcogenide quantum dots; however, a lack of quantifiable data for these processes limits the rational functionalization of nanomaterials. Here, we quantify the X-type ligand exchange reaction between carboxylate-terminated ligands on PbS quantum dots via1H NMR spectroscopy. Using spectroscopic handles of both the native and exchange ligand, bound and free forms of each have been quantified as a function of exchange ligand concentration. We find that the equilibrium constants for the reaction between oleate-capped PbS quantum dots and undec-10-enoic acid are 2.23 ± 0.50 and 2.14 ± 0.42 for sets of nanocrystals prepared by two different synthetic methods. X-ray photoelectron, absorbance, and emission spectroscopies indicate that the carboxylate exchange reaction does not alter the lead ion coverage of the nanocrystal surface. The quantitative equilibrium constant determined herein can be used to improve control over partial ligand exchange reactions on PbS nanocrystals.

METHODS OF PRODUCING METAL SUFLIDES, METAL SELENIDES, AND METAL SULFIDES/SELENIDES HAVING CONTROLLED ARCHITECTURES USING KINETIC CONTROL

The present invention is directed to methods of preparing metal sulfide, metal selenide, or metal sulfide/selenide nanoparticles and the products derived therefrom. In various embodiments, the nanoparticles are derived from the reaction between precursor metal salts and certain sulfur- and/or selenium-containing precursors each independently having a structure of Formula (I), (II), or (III), or an isomer, salt, or tautomer thereof, where Q1,Q2,Q3,R1,R2,R3,R5, and X are defined within the specification.

3D assembly of all-inorganic colloidal nanocrystals into gels and aerogels

We report an efficient approach to assemble a variety of electrostatically stabilized all-inorganic semiconductor nanocrystals (NCs) by their linking with appropriate ions into multibranched gel networks. These all-inorganic non-ordered 3D assemblies benefit from strong interparticle coupling, which facilitates charge transport between the NCs with diverse morphologies, compositions, sizes, and functional capping ligands. Moreover, the resulting dry gels (aerogels) are highly porous monolithic structures, which preserve the quantum confinement of their building blocks. The inorganic semiconductor aerogel made of 4.5 nm CdSe colloidal NCs capped with I- ions and bridged with Cd2+ ions had a large surface area of 146 m2 g-1. An assembly approach for a variety of electrostatically stabilized all-inorganic semiconductor nanocrystals is based on their linking with appropriate ions into multibranched gel networks. The resulting aerogels are highly porous monolithic structures, which preserve the quantum confinement of their building blocks.

Simultaneous ligand and cation exchange in PbSe/CdSe nanocrystal films

Trap states formed at the surface of colloidal semiconductor nanocrystals can have deleterious impact on performance in emerging optoelectronic applications. To mitigate surface traps in nanocrystal thin films we investigated simultaneous surface passivation and ligand exchange for PbSe nanocrystal films via treatment with a cadmium acetate solution. We show that a kinetically limited surface cation exchange produces a thin CdxPb1 -xSe shell that effectively passivates the nanocrystal surface as confirmed by increased photoluminescence intensity and photoluminescence lifetime. Ligand exchange to acetate ligands is confirmed via Fourier transform infrared spectroscopy and grazing incidence small angle X-ray scattering. We studied the impact of the cadmium acetate treatment on interparticle coupling and found that the reduced interparticle spacing and limited shell thickness leads to increased F?rster resonant energy transfer in nanocrystal films. Simultaneous cation/ligand exchange enables the production of heterostructured nanocrystal films with properties like Quasi-Type II nanocrystals synthesized in solution.

A Tunable library of substituted thiourea precursors to metal sulfide nanocrystals

Controlling the size of colloidal nanocrystals is essential to optimizing their performance in optoelectronic devices, catalysis, and imaging applications. Traditional synthetic methods control size by terminating the growth, an approach that limits the reaction yield and causes batch-to-batch variability. Herein we report a library of thioureas whose substitution pattern tunes their conversion reactivity over more than five orders of magnitude and demonstrate that faster thiourea conversion kinetics increases the extent of crystal nucleation. Tunable kinetics thereby allows the nanocrystal concentration to be adjusted and a desired crystal size to be prepared at full conversion. Controlled precursor reactivity and quantitative conversion improve the batch-tobatch consistency of the final nanocrystal size at industrially relevant reaction scales.

Characterisation of metal carboxylates by Raman and infrared spectroscopy in works of art

This work introduces the complementary use of μ-Raman and μ-Fourier transform infrared (IR) spectroscopy for the detection of specific carbon chains and cations for the identification of metal carboxylates within oil paint microsamples. Metal carboxylates (metal soaps) form naturally when free fatty acids react with metal cations and may also be found as additives or degradation products. Twenty-two metal carboxylates were synthesised, and their spectra assembled in a reference database. Metal salts of cations commonly present in oil paintings were used, including lead, zinc, calcium, cadmium, copper and manganese. The fatty acids selected were the saturated acids palmitic (C1 6:0) and stearic (C18:0) and the polyunsaturated oleic acid (C1 8:1). Azelaic acid (C9 diacid), a product resulting from autoxidation of polyunsaturated acids, was also included. Metal carboxylates were characterised by Raman and IR spectroscopy, and their structures were confirmed by X-ray diffraction. Raman and IR spectroscopy proved to be complementary techniques for a full identification of the metal carboxylates in complex aged paint. Raman enables the differentiation of the carbon chain length in the C-C stretching region (1120-1040 cm-1), and IR distinguishes the metal cation in the COO- stretching absorption region (1650-1380cm-1). Principal component analysis was applied to the spectra in order to facilitate a fast and accurate method to discriminate between the different metal carboxylates and to aide in their identification. Finally, spectra from case studies were successfully projected in the principal component analysis models built, enabling a higher confidence level for the identification of copper palmitate and copper azelate in two 19th-century Portuguese oil paintings.

Quantum confinement-tunable ultrafast charge transfer at the PbS quantum dot and phenyl-C61-butyric acid methyl ester interface

Quantum dot (QD) solar cells have emerged as promising low-cost alternatives to existing photovoltaic technologies. Here, we investigate charge transfer and separation at PbS QDs and phenyl-C61-butyric acid methyl ester (PCBM) interfaces using a combination of femtosecond broadband transient absorption (TA) spectroscopy and steady-state photoluminescence quenching measurements. We analyzed ultrafast electron injection and charge separation at PbS QD/PCBM interfaces for four different QD sizes and as a function of PCBM concentration. The results reveal that the energy band alignment, tuned by the quantum size effect, is the key element for efficient electron injection and charge separation processes. More specifically, the steady-state and time-resolved data demonstrate that only small-sized PbS QDs with a bandgap larger than 1 eV can transfer electrons to PCBM upon light absorption. We show that these trends result from the formation of a type-II interface band alignment, as a consequence of the size distribution of the QDs. Transient absorption data indicate that electron injection from photoexcited PbS QDs to PCBM occurs within our temporal resolution of 120 fs for QDs with bandgaps that achieve type-II alignment, while virtually all signals observed in smaller bandgap QD samples result from large bandgap outliers in the size distribution. Taken together, our results clearly demonstrate that charge transfer rates at QD interfaces can be tuned by several orders of magnitude by engineering the QD size distribution. The work presented here will advance both the design and the understanding of QD interfaces for solar energy conversion.

Role of organosulfur compounds in the growth and final surface chemistry of PbS quantum dots

This paper describes the mechanism by which reaction of sulfur with 1-octadecene (ODE) induces a change in the shape of PbS quantum dots (QDs), synthesized from the S/ODE precursor and lead(II) oleate, from cubic to hexapodal by altering the ligand chemistry of the growing QDs. 1H NMR and optical spectroscopies indicate that extended heating of sulfur and ODE at 180 °C produces a series of organosulfur compounds with optical transitions in the visible region and that the binding of organosulfur ligands to the growing QD induces a preferential growth at the 100 faces (over the 111 faces) and, therefore, a hexapodal geometry for the particles. The study shows that S/ODE can be made a more reliable precursor by reducing the temperature and duration of the sulfur dissolution step and that any metal sulfide QD synthesis using elemental sulfur heated to high temperatures should take steps to reduce the in situ yield of organosulfur byproducts by avoiding olefinic solvents.