Photonic bandgap of inverse opals prepared from core-shell spheres

Abstract

In this study, we synthesized monodispersed polystyrene (PS)-silica core-shell spheres with various shell thicknesses for the fabrication of photonic crystals. The shell thickness of the spheres was controlled by various additions of tetraethyl orthosilicate during the shell growth process. The shrinkage ratio of the inverse opal photonic crystals prepared from the core-shell spheres was significantly reduced from 14.7% to within 3%. We suspected that the improvement resulted from the confinement of silica shell to the contraction of PS space during calcination. Due to the shell effect, the inverse opals prepared from the core-shell spheres have higher filling fraction and larger wavelength of stop band maximum.

Filling in the gaps: The nature of light transmission through solvent-filled inverse opal photonic crystals

“…This method requires a known value for 𝑛 eff , and assumes a perfectly filled IO structure with 𝜑 IO = 0.26. Some reports [53][54][55][56] have suggested that inverse opals feature a less than an optimal filling fraction. A variation to the filling fraction 𝜑 IO of an IO would prevent an accurate determination of 𝑛 eff via Eqs.…”

“…In other cases [50,51], such as those with inverse opals prepared via annealing an opal template, there is a clear difference between the estimation of material properties from the spectral data and the independently measured microscopy data. It has been suggested that the optical behavior of inverse opal materials is inherently different from the reciprocal of an opal, with the possibility of an axial compression [51], reduced unit cell parameter [52] and, most commonly, reduced crystalline material volume fractions [53][54][55][56][57] suggested as possible explanations. Currently, there is an absence of consensus on the explanation underpinning the differences observed in the PBG for inverse opal structures.…”

Optoelectrical Regulation of CuBi2O4 Photocathode via Photonic Crystal Structure for Solar–Fuel Conversion

“…First is the vertical self-assembly of PS spheres onto the clean ITO substrate as sacrificial templates. The photonic bandgap of io-CBO can be adjusted by varying the size of PS spheres (200 and 400 nm) . Second is the infiltration of CBO precursors into the voids of PS templates.…”

“…The photonic bandgap of io-CBO can be adjusted by varying the size of PS spheres (200 and 400 nm). 26 Second is the infiltration of CBO precursors into the voids of PS templates. Third is the removal of PS spheres by calcination in the air to obtain CBO inverse opals.…”