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Hybrid Ligand Exchange of Cu(In,Ga)S <sub/>2</sub> Nanoparticles for Carbon Impurity Removal in Solution Processed Photovoltaics
摘要： The solution processing of Cu(In,Ga)(S,Se)2 photovoltaics from colloidal nanoparticles has long suffered from deleterious carbonaceous residues originating from long chain native ligands. This impurity carbon has been observed to hinder grain formation during selenization and leave a discrete residue layer between the absorber layer and the back contact. In this work, organic and inorganic ligand exchanges were investigated to remove tightly bound native oleylamine ligands from Cu(In,Ga)S2 nanoparticles, thereby removing the source of carbon contamination. However, incomplete ligand removal, poor colloidal stability, and/or selective metal etching was observed for these methods. As such, an exhaustive hybrid organic/inorganic ligand exchange was developed to bypass the limitations of individual methods. A combination of microwave-assisted solvothermal pyridine ligand stripping followed by inorganic capping with diammonium sulfide was developed and yielded greater than 98% removal of native ligands via a rapid process. Despite the aggressive ligand removal, the nanoparticle stoichiometry remained largely unaffected when making use of the hybrid ligand exchange. Furthermore, highly stable colloidal ink formulations using non-toxic dimethyl sulfoxide were developed, supporting stable nanoparticle mass concentrations exceeding 200 mg/mL. Scalable blade coating of the ligand exchanged nanoparticle inks yielded remarkably smooth and microcrack free films with RMS roughness less than 7 nm. Selenization of ligand exchanged nanoparticle films afforded substantially improved grain growth as compared to conventional non-ligand exchanged methods yielding an absolute improvement in device efficiency of 2.8%. Hybrid ligand exchange nanoparticle based devices reached total-area power conversion efficiencies of 12.0%, demonstrating the feasibility and promise of ligand exchanged colloidal nanoparticles for the solution processing of Cu(In,Ga)(S,Se)2 photovoltaics.
关键词： hybrid ligand exchange,blade coating,diammonium sulfide,carbon impurity removal,photovoltaics,grain growth,Cu(In,Ga)(S,Se)2,solution processing,ligand exchange,selenization,microwave-assisted solvothermal,colloidal nanoparticles,device efficiency
更新于2025-09-23 15:21:01
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Sputtered p-type Cu <sub/>x</sub> Zn <sub/>1-x</sub> S back contact to CdTe solar cells
摘要： As thin film cadmium telluride (CdTe) solar cells gain prominence, one particular challenge is optimizing contacts and their interfaces to transfer charge without losses in efficiency. Back contact recombination is still significant and will prevent CdTe solar technology from reaching its full potential in device efficiency, and transparent back contacts have not been developed for bifacial solar technology or multijunction solar cells. To address these challenges, this study investigates sputtered CuxZn1-xS as a p-type semi-transparent back contact material to thin film polycrystalline CdTe solar cells, at Cu concentrations x = 0.30, 0.45 and 0.60. This material is selected for its high hole conductivity (160 to 2,120 S cm-1), wide optical band gap (2.25 to 2.75 eV), and variable ionization potential (approximately 6 to 7 eV) that can be aligned to that of CdTe. We report that without device optimization, CdTe solar cells with these CuxZn1-xS back contacts perform as well as control cells with standard ZnTe:Cu back contacts. We observe no reduction in external quantum efficiency, low contact barrier heights of approximately 0.3 eV, and carrier lifetimes on par with those of baseline CdTe. These cells are relatively stable over one year in air, with VOC and efficiency of the x = 0.30 cell decreasing by only 1% and 3%, respectively. Using SEM and STEM to investigate the CuxZn1-xS?CdTe interface, we demonstrate that the CuxZn1-xS layer segregates into a bilayer of Cu-Te-S and Zn-Cd-S, and thermodynamic reaction calculations support these findings. Despite its bilayer formation, the back contact still functions well. This investigation explains some of the physical mechanisms governing the device stack, inspires future work to understand interfacial chemistry and charge transfer, and elicits optimization to achieve higher efficiency CdTe cells.
关键词： solar cell back contact design,transparent semiconductors,copper zinc sulfide,solar cell interfaces,CdTe photovoltaics
更新于2025-09-23 15:21:01
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Fragmentation of Magica??Size Cluster Precursor Compounds into Ultrasmall CdS Quantum Dots with Enhanced Particle Yield at Low Temperatures
摘要： Colloidal small-size CdS quantum dots (QDs) are produced usually with low particle yield, together with side products such as the particular precursor compounds (PCs) of magic-size clusters (MSC). Here, we report our synthesis of small-size CdS QDs without the coexistence of the PC and thus with enhanced particle yield. For a conventional reaction of cadmium oleate (Cd(OA)2) and sulfur (S) in 1-octadecene (ODE), we show that after the formation of the PC in the pre-nucleation stage, the addition of tri-n-octylphosphine oxide (TOPO) facilitates the production of small-size QDs. We demonstrate that TOPO fragmentizes the PC that have formed, which enables the nucleation and growth of small-size QDs even at room temperature. Our findings introduce a new approach to making small-size QDs without the coexistence of the PC and with improved particle yield. Providing experimental evidence for the two-pathway model proposed for the pre-nucleation stage of colloidal binary QDs, the present study aids in the advance of non-classical nucleation theory.
关键词： crystal growth,nucleation,cadmium sulfide,magic-size clusters,quantum dots
更新于2025-09-23 15:21:01
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Quantum Dota??Catalyzed Photoreductive Removal of Sulfonyla??Based Protecting Groups
摘要： This communication describes the use of CuInS2/ZnS quantum dots (QDs) as photocatalysts for the reductive deprotection of aryl sulfonyl-protected phenols. For a series of aryl sulfonates with electron-withdrawing substituents, the rate of deprotection for the corresponding phenyl aryl sulfonates increases with decreasing electrochemical potential for the two electron transfers within the catalytic cycle. The rate of deprotection for a substrate that contains a carboxylic acid, a known QD-binding group, is accelerated by more than a factor of ten from that expected from the electrochemical potential for the transformation, a result that suggests that formation of metastable electron donor-acceptor complexes provides a significant kinetic advantage. This deprotection method does not perturb the common NHBoc or toluenesulfonyl protecting groups and, as demonstrated with an estrone substrate, does not perturb proximate ketones, which are generally vulnerable to many chemical reduction methods used for this class of reactions.
关键词： Copper Indium Sulfide,Photocatalysis,Phenylsulfonates,Deprotection,Quantum dots
更新于2025-09-23 15:21:01
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Photoluminescence of (Zn, Pb, Mn)S Quantum Dots in Polyacrylate Matrix
摘要： Solutions of (Zn, Pb, Mn)S quantum dots with different molar ratios between cations are produced by colloidal synthesis in a methyl methacrylate (MMA) medium. By the thermal polymerization of MMA in a block, the colloidal solutions are converted into the vitreous state. The optical transparency of the poly(MMA)/(Zn, Pb, Mn)S composites at the wavelengths >500 nm reaches 90% at a thickness of the absorbing layer up to 5 mm. The photoluminescence of the composites in the spectral range 400–480 nm is defined by the recombination of electrons at the levels of defects of the ZnS crystal structure, and photoluminescence in the range 520–620 nm by the 4T1 → 6A1 electronic transition in Mn2+ ions. Photoluminescence excitation is a result of interband transitions in ZnS, with energy transfer from the conduction band of ZnS to the levels of Mn2+ ions. The luminescence spectrum depends on the molar ratio between Mn2+ and Pb2+ ions, the order of introduction of substances into the reaction mixture, and the excitation-radiation wavelength.
关键词： acrylate composites,lead ions,doping,luminescence,manganese ions,zinc sulfide,quantum dots
更新于2025-09-23 15:21:01
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Fragmentation of Magica??Size Cluster Precursor Compounds into Ultrasmall CdS Quantum Dots with Enhanced Particle Yield at Low Temperatures
摘要： Colloidal small-size CdS quantum dots (QDs) are produced usually with low particle yield, together with side products such as the particular precursor compounds (PCs) of magic-size clusters (MSC). Here, we report our synthesis of small-size CdS QDs without the coexistence of the PC and thus with enhanced particle yield. For a conventional reaction of cadmium oleate (Cd(OA)2) and sulfur (S) in 1-octadecene (ODE), we show that after the formation of the PC in the pre-nucleation stage, the addition of tri-n-octylphosphine oxide (TOPO) facilitates the production of small-size QDs. We demonstrate that TOPO fragmentizes the PC that have formed, which enables the nucleation and growth of small-size QDs even at room temperature. Our findings introduce a new approach to making small-size QDs without the coexistence of the PC and with improved particle yield. Providing experimental evidence for the two-pathway model proposed for the pre-nucleation stage of colloidal binary QDs, the present study aids in the advance of non-classical nucleation theory.
关键词： crystal growth,nucleation,cadmium sulfide,magic-size clusters,quantum dots
更新于2025-09-23 15:21:01
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Design, synthesis, crystal structure and cytotoxicity studies of colorimetric fluorescent “OFF-ON” probes for rapid detection of hydrogen sulfide based on Cu(II) complex
摘要： Four colorimetric fluorescent probes based on copper(II) complexes were synthesized and the molecular structures were characterized by X-ray diffraction, ESI-HRMS and elemental analysis. When exposed to HS–, the synthesized probes showed significant color changes from yellow to red and remarkable increase of fluorescence intensity (over 80-fold). What’s more, the interaction of host-guest could be completed in 2 minutes. However, no clear color and fluorescence intensity changes were observed in the presence of other anions (AcO–, H2PO4–, F–, Cl–, Br–, I–, SO42-, SO32-, CO32-, Cys and GSH). The synthesized colorimetric fluorescent probes could detect HS– rapidly and conveniently. Cytotoxicity studies indicated that the synthesized fluorescent probes were low cytotoxicity in Hela cells and may be used to detect H2S level in vivo.
关键词： hydrogen sulfide,copper complex crystal,fluorescent probe,colorimetric detection,cytotoxicity
更新于2025-09-23 15:21:01
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Cadmium Sulfide Quantum-Dot-Photocatalyzed Cascade Cyclization of Functionalized Difluoromethyl Chlorides with Unactivated Olefins
摘要： A cadmium sulfide quantum-dot-photocatalyzed C(sp3)?Cl bond cleavage of ethyl chlorodifluoroacetate and cascade cyclization with unactivated olefins is described herein. This reaction provides a cost-efficient method for synthesizing a wide range of CF2-containing azaheterocycles from functionalized difluoromethyl chlorides. Furthermore, the results of a preliminary anti-proliferative activity study indicate an in vitro anti-proliferative activity superior to that of doxorubicin with IC50 values of 1.140 μM on triple negative breast cancer (MDA-MB-231) and 2.129 μM on lung (A549) carcinoma cells.
关键词： anti-proliferative activity,photocatalysis,C(sp3)-Cl activation,fluorine,cadmium sulfide quantum dots
更新于2025-09-23 15:21:01
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Photoelectrochemical performances of Fe2O3 nanotube films decorated with cadmium sulfide nanoparticles via photo deposition method
摘要： Hematite is an appropriate compound for photoelectrochemical water splitting. However, passive surface state, high recombination rate of the photo induced electron-hole pairs and poor and slow charge transfer kinetics restrict the performance of hematite. In this work, CdS/Fe2O3NTs samples have been successfully prepared by coating of CdS nanoparticles on the surface of the self-organized Fe2O3NTs via photo deposition technique in order to enhance charge separation and charge transfer kinetics. FESEM (Field Emission Scanning Electron Microscopy), XRD (X-ray diffraction), DRS (Diffraction Reflection Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy) analyses have been used to characterize the CdS/Fe2O3NTs photoelectrodes obtained. CdS/Fe2O3NTs has an intense visible light absorption and displays a red-shift of the band edge in comparison with the bare Fe2O3NTs, according to DRS test. The photocurrent density of Fe2O3NTs increased approximately 5 times upon coating with CdS, as shown by photoelectrochemical measurements, indicating the significant role of the introduction of CdS in the enhancement of photo catalytic activity. CdS/Fe2O3NTs may be promising and effective photoanodes in PEC water splitting given their simple preparation and good performance.
关键词： Cadmium sulfide,Photo deposition,Fe2O3 nanotube,Photoelectrochemical water splitting
更新于2025-09-23 15:21:01
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Electrochemical Exfoliation of MoS <sub/>2</sub> Crystal for Hydrogen Electrogeneration
摘要： Transition metal dichalcogenides (TMDs) have recently emerged within the group of 2D materials due to their electrical, catalytic and optical properties significantly enhanced and useful when down-sized to single layer. In particular, MoS2 has attracted much attention due to its semiconducting nature with a useful band gap when present as single layer, the enhanced photoluminescence, but also importantly the excellent catalytic properties towards the electrochemical hydrogen evolution. We present here the preparation of thin layers MoS2 nanosheets with enhanced catalytic properties towards the hydrogen evolution reaction by means of an easy and fast electrochemical top-down exfoliation procedure in aqueous solution from a naturally occurring MoS2 crystal. After structural and chemical characterization with STEM, AFM, XPS and Raman spectroscopy electrochemical investigations were performed to test catalytic properties in acidic solution for the electrogeneration of hydrogen and compare it to MoS2 nanosheets obtained through the widely employed chemical Li intercalation/exfoliation. Electrochemically exfoliated MoS2 shows lower Tafel slope than its counterpart obtained with chemical exfoliation.
关键词： hydrogen evolution reaction,molybdenum sulfide,electrochemistry,layered compound,exfoliation
更新于2025-09-23 15:21:01