Mesoporous Bragg Reflectors: Block-copolymer Self-assembly Leads to Building Blocks with Well Defined Continuous Pores and High Control Over Optical Properties

摘要

Mesoporous distributed Bragg reflectors (MDBRs) exhibit porosity on the sub-optical length scale. This makes them ideally suited as sensing platforms in biology and chemistry as well as for light management in optoelectronic devices. Here we present a new fast forward route for the fabrication of MDBRs which relies on the self-assemblingproperties of the block copolymer poly(isoprene-block-ethylene oxide) (PI-b-PEO) in combination with sol-gelchemistry. The interplay between structure directing organic host and co-assembled inorganic guest allows the fine tuning of refractive index in the outcome material. The refractive index diff erence between the high and low porosity layer can be as high as 0.4, with the optical interfaces being well de fined. Following a 30 min annealingprotocol after each layer deposition enables the fast and reliable stacking of MDBRs which exhibit a continuousTiO2 network with large accessible pores and high optical quality.