Novel fabrication of 2D and 3D inverted opals and their application.

solar cells, [ 4 ] and photonic crystals, [ 5 ] 2D hexagonal structures and 3D inverted opal (IO) structures have recently been intensively studied. In order to fabricate uniform IO structures consisting of regular arrangements of spherical void spaces surrounded by solid walls, 2D and 3D colloidal crystals consisting of a regular arrangement of uniform spherical particles are required. To date, a number of techniques to assemble colloidal particles into 2D and 3D opals have been developed: 3D colloidal crystals have been fabricated by sedimentation, [ 6 ] convective assembly, [ 7 ] and electrophoretic deposition, [ 8 ] while 2D colloidal crystals are produced by confi ned convective assembly. [ 9 ] Generally, 2D colloidal crystals have been used to fabricate 2D structures through edge spreading lithography, [ 10 ] colloidal masking, and templating while 3D colloidal crystals have been independently utilized to construct 3D structures through infi ltration and templating. [ 11 , 12 ]