Polymer Distributed Bragg Reflectors for Vapor Sensing

Abstract

We establish a new strategy to achieve fast and responsive hybrid distributed Bragg reflectors for environmental vapor sensing. We fabricated easily processable zinc oxide-polystyrene nanocomposites to grow high quality multilayers with large gas permeability and dielectric contrast, which enable fast and sensitive detection of vapor analytes. Multilayers fabricated by simple spin-coating of the nanocomposite and cellulose acetate show a 10-fold enhancement of the optical response to toluene exposure compared to reference distributed Bragg reflectors built with bare. polystyrene

High refractive index hyperbranched polyvinylsulfides for planar one‐dimensional all‐polymer photonic crystals

“…This interpretation is confirmed by theoretical calculation of the optical response (Fig. SI1 of Supporting Information), reproducing the spectra by using the complex refractive index of HB‐PVS reported in Figure 353 and CA for film thicknesses d HB‐PVS = 104 nm and d CA = 142 nm as input. The spectral tunability of the PBG can be obtained by changing the polymer concentration and/or the spinning velocity as shown in Supporting Information Fig.…”

“…The very good homogeneity combined with the very high reflectance intensity (measured above 70%, 76% calculated from eq ) is indicative of the quality of the prepared DBR. For this kind of structures, the presence of second order diffraction peaks is also expected, being an even tighter fingerprint of optical quality . In our samples, characterized by the principal PBG positioned around 760 nm, the second order is expected to be at λ PBG /2–380 nm, which is however resonant with electronic transitions in HB‐PVS, thus almost completely canceling it (except for a weak structure at 400 nm).…”

“…The light source was a combined deuterium–halogen lamp model Micropak DH2000BAL. Collection angle resolved photoluminescence (PL) spectra are excited by a 405 nm CW laser (Oxxius S.A. LBX‐405‐100‐CSB‐PP model) . Steady state PL spectra of HBPVS have been also measured by using a Perkin Elmer MPF‐44A spectrofluorimeter with excitation at 300 nm.…”

“…The advantages of using polymer PhC instead of more traditional inorganic materials rely on the opportunities provided in terms of low processing cost, large area, low weight, mechanical flexibility, and possibility to have free‐standing structures suitable for postgrowth adhesion on preformed surfaces. This allows for the development of novel strategies for technological applications in the fields of bendable lasers, sensors, fabric, and photovoltaic devices …”

“…By considering photonic crystal structures solely composed of polymer films, the main growth techniques usually adopted are based on block‐copolymers self‐assembly, coextrusion, and spin coating, even though expensive and time consuming ones like holographic lithography, or plasma vapor deposition (a technique suitable for radical polymerization only) are also used. Among them, spin coating allows for a fast and simple preparation of one‐dimensional (1D) planar PhC structures such as Distributed Bragg Reflectors (DBR, multilayers of two alternated materials) and microcavities (for an extended review on this topics, see ref.…”