Synthesis of Exciton Luminescent ZnO Nanocrystals Using Continuous Supercritical Microfluidics

Abstract

ZnO‐Nanokristalle hoher Qualität und mit rein UV‐emittierenden Eigenschaften wurden in einem neuen Mikrofluidikverfahren hergestellt, das überkritische Fluide verwendet und Keimbildungs‐/Wachstums‐ und Funktionalisierungsschritt trennt (siehe Bild). Diese ZnO‐Nanokristalle (NCs) zeigen Excitonen‐Lumineszenz ohne die klassische Fehlstellen‐Lumineszenz.

Silicon‐Based Dielectric Metamaterials: Focus on the Current Synthetic Challenges

“…[65][66][67][68][69] Supercritical synthesis has been applied to the production of Si nano-and microparticles. Thet hermophysical properties of as upercritical fluid, such as density and viscosity,a re intermediate between the properties of its liquid phase and its gas phase.B yv arying the temperature and pressure in the supercritical domain these properties change continuously from gas-like to liquid-like,w ithout the abrupt discontinuity typical of phase changes.S upercritical fluids are powerful reaction media for the synthesis of nanomaterials;t hey combine high mobility of the reactive species,characteristic of the gas phase,with the possibility to solvate precursors in concentrations comparable to solution chemistry routes.T he combination of these two effects increases the reaction kinetics and allows the efficient synthesis of nanomaterials.…”

“…Thet hermophysical properties of as upercritical fluid, such as density and viscosity,a re intermediate between the properties of its liquid phase and its gas phase.B yv arying the temperature and pressure in the supercritical domain these properties change continuously from gas-like to liquid-like,w ithout the abrupt discontinuity typical of phase changes.S upercritical fluids are powerful reaction media for the synthesis of nanomaterials;t hey combine high mobility of the reactive species,characteristic of the gas phase,with the possibility to solvate precursors in concentrations comparable to solution chemistry routes.T he combination of these two effects increases the reaction kinetics and allows the efficient synthesis of nanomaterials. [65][66][67][68][69] Supercritical synthesis has been applied to the production of Si nano-and microparticles. [35,[70][71][72][73] As for gas-phase synthesis,supercritical synthesis involves the thermal decomposition of aSimolecular precursor.Working at high pressure helps reach the high temperatures necessary for the pyrolysis while simultaneously keeping the molecular precursor solvated.…”

Microfluidic hydrodynamic focusing for synthesis of nanomaterials

“…For example, Roig et al . used coaxial tube devices and synthesized UV-emitting ZnO nanoparticles with pure excitonic photoluminescence for application in UV-LEDs [114]. …”

Luminescence of sensitive materials: towards new optical sensing

“…We studied optical properties of ZnO nanoparticles obtained through organometallic route [8,9] and supercritical fluid route [6,7] as a function of their size and shape. The particle shape control is developed by using different ligands (organometallic route) or precursor concentration and operating parameters as time residence (supercritical fluids route).…”

“…Low operating temperature can result in the appearing of surface and bulk defects. Their existence impacts not only the emission wavelength but also its stability under specific atmosphere [6][7][8][9]. Tunable emission properties of these materials make them potential candidates for highly sensitive thermal, gas or photosensors.…”