| As early as 50 years ago,the first liquid crystal display(LCD)was successfully prepared,and today LCD has been widely used.In liquid crystal display,liquid crystal polymer is very important.With the development,more excellent liquid crystal conjugated polymer(LCCP)has been found,which has attracted much attention in recent years.It has the characteristics of both π-conjugated polymer and liquid crystal polymer.With the research finding that the optoelectronic properties of LCCP are very excellent,it can be applied not only to LCD but also to other light-emitting devices.In order to better realize the performance of LCCP,it is particularly important to study the chain orientation.The most widely used chain orientation process is the rubbing orientation method.For friction orientation substrate layer,polyimide,Poly-phenylene vinylene,poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate)are the most used,people have carried on thorough research on them.Studying also found that there are some shortcomings,so it is very important to study the new substrate layer of friction orientation.This thesis mainly studies the orientation effect,orientation process and the influencing factors of chain orientation when using PFN-Br as the orientation layer and rubbing as orientation method.The specific research contents include following aspects:(1)Using polyfluorene derivative PFN-Br as orientation substrate and friction as orientation method,through polarization absorption and polarization emission test,it can be concluded that PFNBr can make blue light emission liquid crystal conjugate polymer PFO,yellow-green light material F8 BT and red-light blend material F8BT/Red F successfully realize orientation and the orientation effect is good.The surface topography tests were also performed on samples of different materials using atomic force microscopy,and they were all found to have highly uniform surfaces.Based on this substrate,the influence of film thickness on the degree of chain orientation was investigated,and the optimal film thickness corresponding to different luminescent materials was obtained.Finally,the anisotropy of amplified spontaneous emission was tested for PFO and F8 BT after orientation,and it was found that the threshold of amplified spontaneous emission could be reduced by chain orientation.(2)Based on the optimal film thickness explored in the first part,the relationship between the friction times of red,green and blue luminescent materials and the degree of chain orientation was explored by changing the friction times of PFN-Br friction treatment,and the optimal treatment friction times of different luminescent materials were obtained.For PFO and F8 BT under the optimal conditions,their dichromatic ratios of 7.37 and 12.22 are very close to the maximum dichromatic ratios deduced theoretically.Furthermore,the friction times of F8 BT with different film thicknesses were investigated.The optimal friction times of F8 BT with different film thicknesses were the same.(3)Based on the monolayer oriented structure,two-and three-layer oriented structure were fabricated by using PFN-Br as friction-oriented substrate.Using F8 BT as the polymer layer in the bilayer structure,the effect of film thickness on the degree of chain orientation in the bilayer structure was investigated.The absorption anisotropy ratio at the optimal thickness was 11.2,which was close to the highest dichroism ratio of the monolayer structure.Then,a three-layer oriented structure was prepared on the basis of the two-layer structure.Three layers of light-emitting materials with different colors,PFO,F8 BT and F8BT/Red F,were selected.It was proved that each layer of light-emitting material was successfully oriented by testing polarization absorption spectrum and polarization emission spectrum.It is proved that laminated orientation technology is feasible,which is beneficial to the subsequent research of multilayer chain orientation. |
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