Chalcogenide Quantum Dots Research Articles

Photoluminescence Enhancement of NIR‐II Emissive Ag2S Quantum Dots via Chloride‐Mediated Growth and Passivation

AbstractAg2S quantum dots (QDs) with high photoluminescence quantum yield (PLQY) in the second near‐infrared (NIR‐II, 1000–1700 nm) window are urgently pursued. Halide atoms (especially chloride) have been studied as inorganic capping ligands on improving the PLQY of Cd‐, Pb‐based chalcogenide QDs; however, it remains a challenge to well replace the organic ligand with chloride ligand from silver chalcogenide QDs. Herein, a novel strategy to prepare Ag2S QDs with significant photoluminescence (PL) enhancement via chloride‐mediated growth and passivation is demonstrated. The oleylamine and oleate ligands on the surface of silver‐rich Ag2S QDs are readily replaced by chloride ligands due to the smaller size and higher binding affinity with Ag+. Upon partial ligand exchange and chloride passivation, the surface trap states in Ag2S QDs are reduced through a decrease of unsaturated surface Ag atoms. Therefore, Ag2S QDs with approximately 300‐fold enhancement of PL intensity, and a PLQY of 47.6% at 1220 nm emission, and a lifetime of 256 ns are obtained because the nonradiative recombination is inhibited. This work reveals that the passivation of Ag2S QDs with chloride ligands is fully feasible, providing new insights into improving the PLQY of silver chalcogenide QDs.

Ultrafast exciton transport at early times in quantum dot solids.

Quantum dot (QD) solids are an emerging platform for developing a range of optoelectronic devices. Thus, understanding exciton dynamics is essential towards developing and optimizing QD devices. Here, using transient absorption microscopy, we reveal the initial exciton dynamics in QDs with femtosecond timescales. We observe high exciton diffusivity (~102 cm2 s-1) in lead chalcogenide QDs within the first few hundred femtoseconds after photoexcitation followed by a transition to a slower regime (~10-1-1 cm2 s-1). QD solids with larger interdot distances exhibit higher initial diffusivity and a delayed transition to the slower regime, while higher QD packing density and heterogeneity accelerate this transition. The fast transport regime occurs only in materials with exciton Bohr radii much larger than the QD sizes, suggesting the transport of delocalized excitons in this regime and a transition to slower transport governed by exciton localization. These findings suggest routes to control the optoelectronic properties of QD solids.

Multifunctional MnCuInSe/ZnS quantum dots for bioimaging and photodynamic therapy.

In this work, manganese (Mn)-doped CuInSe quantum dots (QDs) with a ZnS passivation layer (MnCuInSe/ZnS) have been synthesized via a one-pot microwave-assisted hydrothermal reaction using glutathione (GSH) as a stabilizer. The MnCuInSe/ZnS core-shell QDs combine magnetic resonance imaging (MRI), excitation-dependent red emission, and reactive oxygen radical generation functions, in which regulation of Mn2+ incorporation leads to synergistic imaging and therapeutic modalities. The MnCuInSe/ZnS QDs exhibit high colloidal and photochemical stability in simulated media and at different pH values. An r2/r1 ratio of 9.99 was calculated from MRI studies suggesting their potential application as dual-modal imaging agents. Based on in vitro tests on Hela, B16, and HepG2 cell lines, it is apparent that MnCuInSe/ZnS QDs impose no significant cytotoxicity in the dark, while they can efficiently generate singlet oxygen radicals for photodynamic therapy of cancers, killing more than 80% of B16 cells within 5min of laser irradiation (671nm, 1W cm-2). Furthermore, in vitro fluorescence imaging and cellular internalization of QDs are examined to visualize cellular uptake and in situ ROS generation. Therefore, this research exemplifies a new set of multifunctional chalcogenide QDs for theranostic applications.

Theoretical prediction and design for chalcogenide-quantum-dot/TiO2 heterojunctions for solar cell applications.

Quantum dot sensitized solar cells have attracted much attention due to their high efficiency of photoelectric conversion and low manufacturing cost. In this study, a series of heterojunction structures with cubic (MA)4 chalcogenide quantum dots adsorbing on the (001) surface of TiO2 were investigated, in order to explore new quantum dot sensitizers for solar cell applications. Our study revealed that sulfide and selenide quantum dots are more suitable for solar energy harvesting, compared to their oxide counterparts, due to their smaller ionization potentials and smaller HOMO-LUMO (highest occupied molecular orbital-lowest unoccupied molecular orbital) gaps, but in general exhibit weaker adsorption on TiO2. M4A3B and M4A2B2 quantum dots were designed in combination with the advantage of higher adsorption stability and photoelectric conversion capability. Our theoretical predictions for the structurally precise chalcogenide systems suggest a possible direction for the design of quantum-dot sensitized solar cells.

Precisely Modulating the Photosensitization Efficiency of Transition-Metal Chalcogenide Quantum Dots toward Solar Water Oxidation.

Precisely modulating the spatial charge migration/separation constitutes the central issue in dictating the solar conversion efficiency of photoelectrochemical (PEC) cells, whereas it still remains a grand challenge. Here, we conceptually demonstrate the construction of hierarchically ordered metal oxide (MO)/transition-metal chalcogenide quantum dots (TMC QDs) multilayered heterostructured photoanodes, that is, MO/[TMC QDs(+)/TMC QDs(-)]n (TMC QDs: CdTe, CdSe, CdS), by a simple and general bottom-up self-assembly route. Tailor-made intrinsically oppositely charged TMC QDs are alternately deposited on the highly ordered MO via a generic ligand-triggered electrostatic interaction to craft heterostructured photoanodes. The charge-transfer pathway stimulated by the photosensitization of TMC QDs is finely tuned by the assembly sequence. The advantageous multilayered nanoarchitecture renders the MO/[TMC QDs(+)/TMC QDs(-)]n photoanodes exhibit substantially enhanced PEC performances under light irradiation, owing to the applicable energy-level configuration and peculiar combination fashion between building blocks and considerably boosted interfacial charge separation resulting from generating spatial tandem charge transport. Furthermore, photosensitization efficiency comparison among TMC QDs is comprehensively performed with PEC mechanisms elucidated.

Polymer‐Mediated Electron Tunneling Towards Solar Water Oxidation

AbstractExploiting emerging artificial photosystems with regulated vectorial charge transfer pathways is retarded by the difficulties in precise interface modulation at the nanoscale level, deficiency of suitable assembly methodologies, and ultra‐short charge lifetime. Herein, it is first conceptually demonstrated the general design of transition metal chalcogenides quantum dots (TMCs QDs)‐insulating polymer‐metal oxides (MOs) electron‐tunneling photosystems, wherein TMCs QDs are controllably layer‐by‐layer self‐assembled on the MOs substrates assisted by an ultrathin insulating polymer interim layer. It is ascertained that electrons photoexcited over TMCs QDs in spatially highly ordered MOs/(TMCs QDs/polymer)n multilayered heterostructures can be unidirectionally extracted and tunneled to the MOs substrates across the intermediate insulating polymer layer by engendering the tandem charge transfer to accelerate the interfacial charge migration kinetics, thereby triggering the significantly boosted net efficiency of solar‐driven photoelectrochemical water oxidation. This study would spark new inspirations for designing novel electron‐tunneling photosystems for fine carrier modulation towards solar energy harvesting and conversion.

Studies on copper indium selenide/Zinc sulphide semiconductor quantum dots for solar cell applications

Despite dedicated efforts to develop efficient quantum dot sensitized (QDS) photovoltaic cells, the efficiency of these cells still lags behind their theoretical value. In order to increase photo conversion efficiency, the extant methods are predominantly focus on modifying the band gaps of quantum dots and optimizing the interfaces of cell components to increase light utilization capacity. In this study, we have designed and investigated QDS solar cells using Copper Indium Selenide (CuInSe2 or simply CIS) as a quantum dot absorber. In order to achieve tunable bandgap, increased photoluminescence, reduced density of surface defect state and higher light-harvesting efficiency, the CuInSe2 is alloying with Zinc sulfide (ZnS) to design Copper Indium Selenide-Zinc sulfide (CISZS) quantum dots. The resulting CISZS sensitizer exhibits improved photoelectric characteristics and greater chemical stability. The performance of the CIS and CISZS solar cells is evaluated individually through Silvaco-Atlas simulation software in terms of measures such as power conversion efficiency, open-circuit voltage (Voc), the density of short-circuit current (Jsc) and fill-factor (FF). The CISZS-based solar cells show an average conversion efficiency of 23.5% (i.e., 4.94% higher than the efficiency of CIS solar cell) with Voc = 0.596V, Jsc = 23.61mA/cm2 and FF = 0.84 under AM 1.5G with a power density of 100mW/cm2 . The achieved power conversion efficiency indicates the greatest performances of the QDS solar cells. These non-toxic photovoltaic devices reveal better optical and electrical properties than toxic lead and cadmium chalcogenide quantum dots absorbers.

Modelling of density of states and energy level of chalcogenide quantum dots

AbstractQuantum dots (QDs) or semiconductor nanocrystals are luminous materials with unique optical properties that can be fine-tuned by varying the size of the material. Chalcogenide QDs show strong quantum confinements effects owing to the fact that the exciton Bohr radius is much larger than the particle size, and tunable energy bandgap leads to widespread technological interest in near-infrared optical devices. In this communication, one dimensional Cu2SnS3and PbSexS1-xQDs is modeled by a particle in a box model which was used to compute energies and density of states. The density of states and the energy level of QDs are determined as a function of the strengths of the potential walls of the inner box. The results exhibit that the density of states decreases exponentially with an increase in the energy level of QDs. The density of states at lower energy levels is more significant than what is observed in higher energy levels.

Highly stable full-color display device with VLC application potential using semipolar μLEDs and all-inorganic encapsulated perovskite nanocrystal

A promising approach for the development of effective full-color displays is to combine blue microLEDs (μLEDs) with color conversion layers. Perovskite nanocrystals (PNCs) are notable for their tolerance to defects and provide excellent photoluminescence quantum yields and high color purity compared to metal chalcogenide quantum dots. The stability of PNCs in ambient conditions and under exposure to blue light can be improved using a SiO 2 coating. This study proposes a device that could be used for both display and visible light communication (VLC) applications. The semipolar blue μLED array fabricated in this study shows a negligible wavelength shift, indicating a significant reduction in the quantum confined Stark effect. Owing to its shorter carrier lifetime, the semipolar μLED array exhibits an impressive peak 3 dB bandwidth of 655 MHz and a data transmission rate of 1.2 Gb/s corresponding to an injection current of 200 mA. The PNC–μLED device assembled from a semipolar μLED array with PNCs demonstrates high color stability and wide color-gamut features, achieving 127.23% and 95.00% of the National Television Standards Committee standard and Rec. 2020 on the CIE 1931 color diagram, respectively. These results suggest that the proposed PNC–μLED device is suitable for both display-related and VLC applications.

One-Pot Synthesis and Structural Evolution of Colloidal Cesium Lead Halide-Lead Sulfide Heterostructure Nanocrystals for Optoelectronic Applications.

Heterostructures, combining perovskite nanocrystals (PNC) and chalcogenide quantum dots, could pave a path to optoelectronic device applications by enabling absorption in the near-infrared region, tailorable electronic properties, and stable crystal structures. Ideally, the heterostructure host material requires a similar lattice constant as the guest which is also constrained by the synthesis protocol and materials selectivity. Herein, we present an efficient one-pot hot-injection method to synthesize colloidal all-inorganic cesium lead halide-lead sulfide (CsPbX3 (X = Cl, Br, I)-PbS) heterostructure nanocrystals (HNCs) via the epitaxial growth of the perovskite onto the presynthesized PbS nanocrystals (NCs). Optical and structural characterization evidenced the formation of heterostructures. The embedding of PbS NCs into CsPbX3 perovskite allows the tuning of the absorption and emission from 400 to 1100 nm by tuning the size and composition of perovskite HNCs. The CsPbI3-PbS HNCs show enhanced stability in ambient conditions. The stability, tunable optical properties, and variable band alignments accessible in this system would have implications in the design of novel optoelectronic applications such as light-emitting diodes, photodetectors, photocatalysis, and photovoltaics.

Carrier Dynamics in Alloyed Chalcogenide Quantum Dots and Their Light‐Emitting Devices

AbstractLight‐emitting devices based on alloyed quantum dots have reached external quantum efficiencies above 20% in red, green, and blue emission devices. Their outstanding performances including high efficiency, long‐term device stability, and suppressed efficiency roll‐off identify alloyed‐quantum‐dot based light‐emitting devices as good candidates for next generation solid‐state lightings and displays. All these advantages stem from the chemical composition gradient of alloyed quantum dots in radial direction. The chemical composition gradient enables the lattice strain to be released gradually, eventually decreasing interface defects and suppressing Auger recombination. Carrier dynamics play a crucial role in the fundamental properties and functionalities of quantum dots for solid‐state devices and light‐emitting devices. A more in‐depth understanding of carrier dynamics in quantum dots is therefore of both fundamental and technological significance. This review article provides an overview on recent advances in the study and understanding of carrier dynamics of alloyed quantum dots and alloyed‐quantum‐dot based light‐emitting devices. Particular emphasis is placed on the relationship between Auger recombination and optical properties and optoelectronic properties. This review is expected to encourage further research in alloyed quantum dots and related devices and to stimulate new synthesis efforts to produce stable alloyed quantum dots with further improved control of carrier dynamics.

MXene-motivated accelerated charge transfer over TMCs quantum dots for solar-powered photoreduction catalysis

Transition metal chalcogenides quantum dots (TMCs QDs) demonstrate emerging potential in solar energy conversion owing to marvelous physicochemical properties, such as quantum size effect, large extinction coefficient, and multiple excitons generation. Nevertheless, TMCs QDs as photosensitizers are unstable owing to high surface energy, and moreover, substantial trap states of TMCs QDs annihilate the photo-induced charge carriers, thus resulting in ultra-short charge lifetime and inferior photoactivities. Herein, 0D/2D TMCs QDs/MXene heterostructures were designed by a ligand-initiated electrostatic self-assembly strategy, wherein positively charged TMCs QDs were anchored on the negatively charged ultrathin Ti3C2Tx nanosheets (NSs) framework, which promotes the anisotropic unidirectional electron transport from TMCs QDs to MXene NSs. MXene functions as an effective charge mediator to decrease the charge recombination and prolong the charge lifetime for photocatalytic hydrogen generation and anaerobic reduction of nitroaromatics to amino compounds under visible light irradiation. Our work would shed new insights on the role of MXene in tuning the directional charge transport for solar energy conversion.

High‐Throughput Robotic Synthesis and Photoluminescence Characterization of Aqueous Multinary Copper–Silver Indium Chalcogenide Quantum Dots

AbstractThe feasibility of a high‐throughput robot‐assisted synthesis of complex Cu1‐xAgxInSySe1‐x (CAISSe) quantum dots (QDs) by spontaneous alloying of aqueous glutathione‐capped Ag–In–S, Cu–In–S, Ag–In–Se, and Cu–In–Se QDs is demonstrated. Both colloidal and thin‐film core CAISSe and core/shell CAISSe/ZnS QDs are produced and studied by high‐throughput semiautomated photoluminescence (PL) spectroscopy. The silver‐copper‐mixed QDs reveal clear evidence of a band bowing effect in the PL spectra and higher average PL lifetimes compared to the counterparts containing silver or copper only. The photophysical analysis of CAISSe and CAISSe/ZnS QDs indicates a composition‐dependent character of the nonradiative recombination in QDs. The rate of this process is found to be lower for mixed copper‐silver‐based QDs compared to Cu‐ or Ag‐only QDs. The combination of the band bowing effect and the suppressed nonradiative recombination of CAISSe QDs is beneficial for their applications in photovoltaics and photochemistry. The synergy of high‐throughput robotic synthesis and a high‐throughput characterization in this study is expected to grow into a self‐learning synthetic platform for the production of metal chalcogenide QDs for light‐harvesting, light‐sensing, and light‐emitting applications.

Breaking through the Size Control Dilemma of Silver Chalcogenide Quantum Dots via Trialkylphosphine-Induced Ripening: Leading to Ag2Te Emitting from 950 to 2100 nm.

Ag2Te is one of the most promising semiconductors with a narrow band gap and low toxicity; however, it remains a challenge to tune the emission of Ag2Te quantum dots (QDs) precisely and continuously in a wide range. Herein, Ag2Te QDs emitting from 950 to 2100 nm have been synthesized via trialkylphosphine-controlled growth. Trialkylphosphine has been found to induce the dissolution of small-sized Ag2Te QDs due to its stronger ability to coordinate to the Ag ion than that of 1-octanethiol, predicated by the density functional theory. By controlling this dissolution effect, the monomer supply kinetics can be regulated, achieving precise size control of Ag2Te QDs. This synthetic strategy results in state-of-the-art silver-based QDs with emission tunability. Only by taking advantage of such an ultrawide emission has the sizing curve of Ag2Te been obtained. Moreover, the absolute photoluminescence quantum yield of Ag2Te QDs can reach 12.0% due to their well-passivated Ag-enriched surface with a density of 5.0 ligands/nm2, facilitating noninvasive in vivo fluorescence imaging. The high brightness in the long-wavelength near-infrared (NIR) region makes the cerebral vasculature and the tiny vessel with a width of only 60 μm clearly discriminable. This work reveals a nonclassical growth mechanism of Ag2Te QDs, providing new insight into precisely controlling the size and corresponding photoluminescence properties of semiconductor nanocrystals. The ultrasmall, low-toxicity, emission-tunable, and bright NIR-II Ag2Te QDs synthesized in this work offer a tremendous promise for multicolor and deep-tissue in vivo fluorescence imaging.

The quantum confinement effect on the spectrum of near-field thermal radiation by quantum dots

The quantum confinement effect on the spectrum of near-field thermal radiation by periodic and random arrays of quantum dots (QDs) is investigated. The local density of states (LDOS) thermally emitted by QD arrays made of three lead chalcogenides, namely, lead sulfide, lead selenide, and lead telluride, is computed at a near-field distance from the arrays. The dielectric function of the QDs is extracted from their absorption spectra by utilizing an optimization technique. The thermal discrete dipole approximation is used for computing the LDOS. It is shown that the peak wavenumber of near-field LDOS emitted by periodic arrays of lead chalcogenide QDs can be significantly modulated (up to 4490 cm−1) by varying the size of the dots. The LDOS is proportional to the imaginary part of the QDs' polarizability, which peaks at the bandgap energy of the QDs. The bandgap energy of the QDs (and thus the LDOS peak) is significantly affected by the quantum confinement effect, which is size dependent. While the magnitude of thermal radiation by random arrays of QDs can be different from the periodic arrays with the same filling factor by up to ±26%, the LDOS spectrum and peak location are the same for both periodic and random arrays. The peak wavenumber of near-field radiative heat transfer between the QD arrays is also strongly affected by quantum confinement in the QDs, and thus, it can be tuned by changing the size of the QDs.

Modulating the 0D/2D Interface of Hybrid Semiconductors for Enhanced Photoelectrochemical Performances.

Photoelectrochemical (PEC) solar-driven hydrogen production is a promising route to convert solar energy into chemical energy using semiconductors as active materials. However, the performance is still far from satisfactory due to a limited absorption range and rapid charge recombination. Compared to 3D semiconductors, 0D/2D nanohybrids may exhibit better PEC performance, due to the formation of an intimate interface between the two semiconductors that can inhibit carrier recombination. Herein, a photoelectrode based on a 0D/2D heterojunction is constructed by 0D metal chalcogenide quantum dots (QDs) and hierarchical 2D Zn-MoS2 nanosheets (NSs). The effect of PbS, CdS, and their composite PbS@CdS QDs is analyzed by depositing them onto Zn-MoS2 NSs using an in situ process. This distinctive heterojunction can leverage the light harvesting capabilities of QDs with the catalytic performance of Zn-MoS2 . Compared to Zn-MoS2 , Zn-MoS2 /PbS, and Zn-MoS2 /CdS, the obtained 0D/2D heterostructure based on the composite Zn-MoS2 /PbS@CdS has a significantly enhanced photocurrent. The synergistic effect between 0D/2D heterojunction, the extended absorption range of QDs, and the strong coupling and band alignment between them lead to superior solar-driven PEC performance. This work can provide a new platform to construct multifunctional 0D/2D nanohybrids for optoelectronic applications, not limited to PEC devices.

Semiconducting Nanoparticles: Single Entity Electrochemistry and Photoelectrochemistry.

Semiconducting nanoparticles (SC NPs) play vital roles in several emerging technological applications including optoelectronic devices, sensors and catalysts. Recent research focusing on the single entity electrochemistry and photoelectrochemistry of SC NPs is a fascinating field which has attained an increasing interest in recent years. The nano-impact method provides a new avenue of studying electron transfer processes at single particle level and enables the discoveries of intrinsic (photo) electrochemical activities of the SC NPs. Herein, we review the recent research work on the electrochemistry and photoelectrochemistry of single SC NPs via the nano-impact technique. The redox reactions and electrocatalysis of single metal oxide semiconductor (MOS) NPs and chalcogenide quantum dots (QDs) are first discussed. The photoelectrochemistry of single SC NPs such as TiO2 and ZnO NPs is then summarized. The key findings and challenges under each topic are highlighted and our perspectives on future research directions are provided.

Light-driven catalytic conversion of CO2 with heterogenized molecular catalysts based on fourth period transition metals

• Dispersions of heterogenized catalysts can benefit photocatalytic CO 2 reduction. • Catalysts can be attached covalently, electrostatically, or non-covalently. • The support material chemistry is important, i.e. band-gap and hydrophobicity. • The same chemistry can be used to attach catalysts to photoelectrodes. • Molecular CO 2 reduction catalysts can be incorporated into MOF and COF frameworks. This review examines recent advances in photocatalytic CO 2 reduction using heterogenized molecular catalysts. The main part of the discussion is focused on the chemistry used to attach catalysts to different supports to produce hybrid materials, and how this effects photocatalytic performance. Examples of hybrid materials used for colloidal dispersions and solid suspensions are presented, including those based on carbon nitride, chalcogenide and perovskite quantum dots, and metal oxides. Some key examples in which this chemistry has been employed to make electrodes and photoelectrodes for photoelectrochemical CO 2 reduction are also presented. In addition, the incorporation of molecular catalysts into ordered, porous frameworks (MOFs and COFs) is discussed because it offers many new and unique chemical pathways for heterogenization. Lastly, an outlook for this field and the potential future impact of these systems on solar fuels research is given.

Electron tunneling through interim ligand layers towards photoredox selective organic transformation

Photocatalytic selective organic transformation represents an emerging avenue for artificial photosynthesis toward renewable solar energy conversion. However, solar-to-chemical conversion efficiency in photocatalysis is largely hampered by the sluggish charge transfer kinetic and difficulty in precise control over the charge migration pathway. Herein, we demonstrate conceptually new metal–insulator–semiconductor (MIS) electron tunneling photosystems to finely modulate the directional charge flow for photoredox selective organic transformation. The ultrathin insulating organic ligands layers capped on the surfaces of metal nanocrystals (NYs) and transition metal chalcogenides quantum dots (TMCs QDs) mutually function as precise directing-mediums to stimulate spontaneous electrostatic self-assembly between the tailor-made oppositely charged metal NYs and TMCs QDs for constructing metal (Au, Pd) NYs/TMCs (CdSe, CdS) QDs heterostructured electron tunneling photosystems. The electrons photoexcited from TMCs QDs can be efficaciously extracted and tunneled to metal NYs across the intermediate insulating hierarchical ligands layers to participate in the photoredox catalysis. The metal NYs-insulating ligands-TMCs QDs photosystems can efficiently mediate the minority carrier transport across the intermediate insulating ligand layers with minimal recombination, thereby resulting in the significantly enhanced net efficiency of multifarious photoactivities toward selective organic transformation including anaerobic photoreduction of nitroaromatics to amino derivatives and selective photo-oxidation of aromatic alcohols to aldehydes under visible light irradiation. The ligand-triggered electron tunneling effect has been evidence to be universal. Our work would inspire ongoing interest in exploring diverse organic ligands-based charge tunneling photosystems and provide a valuable roadmap for substantial solar energy conversion.

Evolution of Two Types of ZnTe Magic-Size Clusters Displaying Sharp Doublets in Optical Absorption.

The two-pathway model proposed for colloidal semiconductor metal chalcogenide (ME) quantum dots (QDs) and magic-size clusters (MSCs) is demonstrated for ZnTe. Two new types of ZnTe MSCs have been found, which exhibit sharp optical absorption doublets peaking at 356/389 and 389/420 nm. Labeled dMSC-389 and dMSC-420, respectively, they were produced from reaction mixtures in 1-octadecene (ODE) of zinc oleate (Zn(OA)2), tri-n-octylphosphine telluride (TeTOP), diphenylphosphine (HPPh2), and acetic acid (HOAc, CH3COOH). The collective use of HOAc and HPPh2 enabled the exclusive production of dMSC-389 and dMSC-420 from reaction mixtures that had high Zn-to-Te feed molar ratios and a high Te feed concentration of 60 mmol/kg. The present findings demonstrate the utility of HOAc in synthesizing MSCs displaying a sharp absorption doublet, as well as of a secondary phosphine that decreases the temperature at which the M-E covalent bonds form.