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Electric-Field Assisted Assembly of Colloidal Particles into Ordered Nonclose-Packed Arrays
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posted on 2017-05-17, 00:00 authored by Jingjing Gong, Ning WuNonclose-packed
colloidal arrays have many potential applications
ranging from plasmonic sensors, light trapping for photovoltaics,
to transparent electrodes. However, scalable fabrication of those
structures remains a challenge. In this Article, we investigate the
robustness of an electric-field assisted approach systematically.
A monolayer of nonclose-packed crystalline array is first created
under a low-frequency alternating-current electric field in solution.
We then apply a sequence of direct-current pulses to fix the particle
array onto the substrate so that it remains intact even after both
field removal and solvent evaporation. Key process parameters such
as the alternating-current field strength, direct-current magnitude,
particle concentration, and solvent-evaporation rate that affect both
ordering and fixing of colloidal particles have been studied systematically.
We find that direct currents with an intermediate magnitude induce
electrophoretic motion of particles toward the substrate and facilitate
their permanent adhesion on the substrate due to strong van der Waals
attraction. A higher current, however, causes lateral aggregation
of particles arising from electroosmotic flow of solvent and destroys
the periodic ordering between particles. This approach, in principle,
can be conveniently adapted into the continuous convective assembly
process, thus making the fabrication of nonclose-packed colloidal
arrays scalable.
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Keywords
electroosmotic flowelectrophoretic motionvan der Waals attractionElectric-Field Assisted Assemblyscalable fabricationparticle arraydirect-current pulsesconvective assembly processKey process parametersNonclose-Packed Arrays Nonclose-packedplasmonic sensorsparticle concentrationsolvent-evaporation ratedirect-current magnitudearrays scalableColloidal Particlessubstratealternating-current field strengthfield removal
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