Abstract
Colloidal quantum-dots (QDs) are highly attractive materials for various optoelectronic applications owing to their easy maneuverability, high functionality, wide applicability, and low cost of mass-production. QDs usually consist of two components: the inorganic nano-crystalline particle and organic ligands that passivate the surface of the inorganic particle. The organic component is also critical for tuning electronic properties of QDs as well as solubilizing QDs in various solvents. However, despite extensive effort to understand the chemistry of ligands, it has been challenging to develop an efficient and reliable method for identifying and quantifying ligands on the QD surface. Herein, we developed a novel method of analyzing ligands in a mild yet accurate fashion. We found that oxidizing agents, as a heterogeneous catalyst in a different phase from QDs, can efficiently disrupt the interaction between the inorganic particle and organic ligands, and the subsequent simple phase fractionation step can isolate the ligand-containing phase from the oxidizer-containing phase and the insoluble precipitates. Our novel analysis procedure ensures to minimize the exposure of ligand molecules to oxidizing agents as well as to prepare homogeneous samples that can be readily analyzed by diverse analytical techniques, such as nuclear magnetic resonance spectroscopy and gas-chromatography mass-spectrometry.
Highlights
IntroductionO O O (e.g., ligand derivatization) prior to GC analysis; this procedure compromises the original chemical integrity of the ligands[16]
O O O prior to GC analysis; this procedure compromises the original chemical integrity of the ligands[16]
We found that hydrogen peroxide (H2O2) is an efficient heterogeneous catalyst to detach most ligands from inorganic parts, while being mild enough to minimize the disruption of their chemical integrity
Summary
O O O (e.g., ligand derivatization) prior to GC analysis; this procedure compromises the original chemical integrity of the ligands[16]. In order to overcome this challenge, we devised a novel protocol of using oxidizing agents to detach organic molecules from the inorganic core or shell surface. Based on previous studies that have demonstrated that oxidation disrupts the interaction between the ligands and n anocrystal[20], we developed a protocol of oxidizing the nanocrystals and subsequently separating the ligand-containing fraction. We found that hydrogen peroxide (H2O2) is an efficient heterogeneous catalyst to detach most ligands from inorganic parts, while being mild enough to minimize the disruption of their chemical integrity. We applied our method to analyze the ligands of InP/ZnS QD samples Despite their overall inferior performance and stability, InP-based QDs have attracted significant interest due to their suitability for environment-friendly a pplication[23,24]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
