Research On Realizing Planar Optical Waveguide Technology By Using Polymer Chain Orientation

Liquid crystal conjugated polymer(LCCP)is a new type of functional material developed in recent years.Its?-electron conjugated system provides conditions for delocalized migration of carriers,so it is often used in the preparation of organic optoelectronic devices.However,the current photoelectric conversion efficiency of liquid crystal conjugated polymer photoelectric materials is generally low,and cannot meet the requirements of industrial applications.Therefore,how to improve the mobility of the device has become a hot research topic.The main channel for carrier migration is an ordered structure,so changing the conjugated polymer into an ordered structure has proven to be an effective way to improve carrier mobility.The liquid crystal conjugated polymer not only has excellent processing properties,but the liquid crystal cell can be spontaneously oriented under the action of external force,electric or magnetic field.In this paper,the orientation of the liquid crystal conjugated polymer is realized by the rubbing alignment and the photoalignment approach,the factors affecting the degree of orientation are studied and the corresponding conclusions are drawn.In addition,we also use the oriented liquid crystal conjugated polymer in optoelectronic devices.The specific research content includes the following aspects:1.Using the rubbing alignment approach,PFN-Br was used as the chain orientation substrate of liquid crystal conjugated polymer for the first time.By measuring the polarization absorption spectrum,it was proved that PFN-Br is an effective rubbing alignment material for LCCP orientation.Based on this substrate,the influence of molecular weight and temperature on the degree of chain orientation was explored,and the temperature gradient heat treatment was performed on F8BT of different molecular weights,and the relationship between the degree of chain orientation of liquid crystal conjugated polymer and molecular weight and its corresponding temperature was obtained.In addition,an atomic force microscope was used to test the surface morphology of samples obtained at different heat treatment temperatures for each molecular weight,and the relationship between surface roughness and morphological changes,molecular weight and heat treatment temperature was obtained.2.By changing the film thickness of the conjugated polymer F8BT,the film thickness relationship of F8BT with different molecular weights at the optimal orientation temperature was explored,and the optimal orientation film thickness of F8BT with each molecular weight at the optimal orientation temperature was obtained.In addition,because F8BT with PFN-Br as the substrate has a good chain orientation effect,and F8BT is a laser gain medium with excellent performance,the ASE phenomenon of F8BT after chain orientation becomes anisotropic,in parallel direction the threshold value of is about 7 times different from the vertical direction,which realizes the preliminary application of chain orientation technology in the laser field.3.Using photoalignment approach,it is proved that SD1 is a high-temperature stable(?265?)light-oriented material for LCCP orientation.Based on the SD1 substrate,the orientation of F8BT is realized,the single-layer and bilayer planar optical waveguides are manufactured using this feature.The A_Absof single-layer planar optical waveguides(150nm)reach 9.7,to A_Abs?11.4 for the bilayer F8BT structure,with optimal LCCP film thickness found to lie within the device relevant 125 to200 nm range.On this basis,we fabricated micro-structured patterned optical waveguides which is difficult for rubbing approach,and photographed the light-dark changes of the optical waveguide with the angle of incident polarized light under an orthogonal polarization microscope.It is expected to be used in optical anti-counterfeiting and stealth technology.