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Copper’s Role in the Photoluminescence of Ag1?xCuxInS2 Nanocrystals, from Copper-Doped AgInS2 (x ~ 0) to CuInS2 (x = 1)
摘要： A series of Ag1?xCuxInS2 nanocrystals (NCs) spanning from 0 ≤ x ≤ ~1 was synthesized by partial cation exchange to identify copper’s contributions to the electronic structure and spectroscopic properties of these NCs. Discrete mid-gap states appear above the valence band (VB) upon doping AgInS2 NCs with Cu+ (small x). Density functional theory (DFT) calculations confirm that these mid-gap states are associated with the 3d valence orbitals of the Cu+ impurities. With increasing x, these impurity d levels gradually evolve to become the VB edge of CuInS2 NCs, but the highest-occupied orbital's description does not change significantly across the entire range of x. In contrast with this gradual evolution, Ag1?xCuxInS2 NC photoluminescence shifts rapidly with initial additions of Cu+ (small x) but then becomes independent of x beyond x > ~0.20, all the way to CuInS2 (x = 1.00). Data analysis suggests small but detectable hole delocalization in the luminescent excited state of CuInS2 NCs, estimated by Monte Carlo simulations to involve at most about four copper ions. These results provide unique insights into the luminescent excited states of these materials and they reinforce the description of CuInS2 NCs as “heavily copper-doped NCs” in which photogenerated holes are rapidly localized in copper 3d-based orbitals.
关键词： silver indium sulfide,nanocrystal,cation exchange,Copper indium sulfide,copper-doped,photoluminescence
更新于2025-09-23 15:23:52
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Bi-Exciton Dissociation Dynamics in Nano-Hybrid Au-CuInS <sub/>2</sub> Nanocrystals
摘要： Multiexciton harvesting from semiconductor quantum dot has been a new approach for improving the solar cell efficiency in Quantum Dot Sensitized Solar Cells (QDSC). Till date, relation between multiexciton dissociation in metal?semiconductor nanohybrid system and boosting the power conversion efficiency (PCE) of QDSC were never discussed. Herein we report a detailed spectroscopic investigation of biexciton dissociation dynamics in copper indium sulfide (CuInS2, also referred as CIS) and Au-CIS nanohybrid, utilizing both time-resolved PL and ultrafast transient absorption (TA) techniques. Ultrafast transient absorption suggests the formation of bi-exciton in CIS NCs which efficiently dissociates in Au-CIS nanohybrids. Maximum multiexciton dissociation (MED) efficiency is determined to be ~ 80% at higher laser fluency, however it was observed to be 100% at lower laser fluency. Prior to exciton dissociation electrons are captured by Au NP in the nanohybrid from the conduction band of CIS NCs which is energetically higher than Fermi level of Au. Here we demonstrate the proof-of-concept in multi-electron dissociation which may provide a new approach for improving the efficiency in QDSSCs, where we found power conversion efficiency (PCE) of Au-CIS nanohybrids up to 2.49% as compared to ~1.06% ~for pure CIS NCs in similar condition. This finding can be an efficient approach towards the design and development of efficient solar cell and optoelectronic devices using the principles of multiexciton generation and extracting multiexcitons in metal-semiconductor nanohybrid system.
关键词： copper indium sulfide,biexciton dissociation dynamics,Quantum Dot Sensitized Solar Cells,power conversion efficiency,ultrafast transient absorption,Multiexciton harvesting,Au-CIS nanohybrid
更新于2025-09-23 15:21:21
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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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Biocompatible off-stoichiometric copper indium sulfide quantum dots with tunable near-infrared emission <i>via</i> aqueous based synthesis
摘要： The present study reports an aqueous synthesis approach towards off-stoichiometric copper indium sulfide quantum dots with emissions in the near-infrared spectral range. The photoluminescence properties of the dots, and in particular the appearance of dual emission at high Cu deficiency, were studied with temperature-dependent steady-state and transient photoluminescence spectroscopy.
关键词： aqueous synthesis,copper indium sulfide,quantum dots,near-infrared emission,photoluminescence
更新于2025-09-12 10:27:22