Antireflective
Coatings with Adjustable Refractive Index and Porosity Synthesized
by Micelle-Templated Deposition of MgF<sub>2</sub> Sol Particles
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Abstract
Minimizing efficiency losses caused
by unwanted light reflection at the interface between lenses, optical
instruments and solar cells with the surrounding medium requires antireflective
coatings with adequate refractive index and coating thickness. We
describe a new type of antireflective coating material with easily
and independently tailorable refractive index and coating thickness
based on the deposition of colloidal MgF<sub>2</sub> nanoparticles.
The material synthesis employs micelles of amphiphilic block copolymers
as structure directing agent to introduce controlled mesoporosity
into MgF<sub>2</sub> film. The coatings thickness can be easily adjusted
by the applied coating conditions. The coatings refractive index is
determined by the materials porosity, which is controlled by the amount
of employed pore template. The refractive index can be precisely tuned
between 1.23 and 1.11, i.e., in a range that is not accessible to
nonporous inorganic materials. Hence, zero reflectance conditions
can be established for a wide range of substrate materials