Preparation And Applacation On One-Dimensional Photonic Crystals Film Derived From Polymer Precusors

One-dimensional photonic crystals(1DPCs)are the simplest structure in photonic crystals due to their simple preparing process,wide material aspects and easy control of structural color.Rigid substrates with flat and smooth surfaces are often used to prepare 1DPCs,but it is difficult to obtain flexible films,let alone self-supporting flexible films.To solve this problem,in this thesis,flexible 1DPCs were constructed via solution process,and the structural color was regulated by controlling the thickness of different components to obtain self-supporting flexible films.In this paper,Bragg stacks SiO_x/TiO_xwere obtained by alternately spin-coating and curing perhydropolysilazane(PHPS)and titanium tetra-n-butoxide(TBT)solution on flexible substrates respectively.Meanwhile,both materials and substrates were closely combined.1DPCs were constructed through multiple stacks,and the effects of precursor concentration,incident light direction,and bending deformation on the photonic bandgap were investigated.It was found that increasing precursor concentration,that is enhancing the thickness of lays will lead to the red shift of the photon bandgap,while increasing the incident light angle and bending deformation will lead to blue shift of the bandgap,which is in line with the angular dependence described by the Bragg diffraction equation.By adjusting the thickness,flexible SiO_x/TiO_xfilms with bright structural colors were achieved.Based on the high reflectivity,angle dependence,and excellent structural stability of the films,SiO_x/TiO_xfilms would have great application potential in the fields of anti-counterfeiting,light filtering,and decoration.Although the above-mentioned SiO_x/TiO_xfilms have achieved much stable flexibility,they are still limited by the substrates.In order to obtain a much greater self-supporting flexible 1DPCs film with separated completely from the substrate,the solution method was adopted in this paper,and polyimide(PI)obtained by thermal curing of polyamide acid(PAA)was used as a high refractive index material to alternately construct 1DPCs films with SiO_x.We selected PI as the first layer,and utilized the hydrophobicity of PI in deionized water to achieve rapid separation of the film from the substrate.Then the film was transferred on a hydrophobic substrate after the surface water evaporates,a self-supporting flexible film that can be picked up with a nipper can be obtained.In this paper,the effects of precursor concentration,rotation speed,incident light angle,bending deformation and extreme environment on the optical properties of thin films were also studied in detail.The inorganic materials involved in this paper have a continuous and dense structure,which is different from the nanoparticle structure,so polydimethylsiloxane(PDMS)is not used as fillers to maintain structural stability,and at the same time,the immersion of fillers is avoided.The occurrence of changing the photonic bandgap.Therefore,this paper realizes flexible film with good structural stability in practice.