| Single white light-emitting polymers have drawn tremendous attention due to its potential application in the field of lighting and display.The design of the molecular structure is fundamental factor affecting the light-emtting device efficiency.The branched structure and three dimentional conformations can effectively alleviate the intense intermolecular interaction and make star-shape/hyper-branched polymers possess good emitting properties.However,the design of the star-shape molecular mainly concentrates on the modification of the guest core units,and the branched content of the polymer is not high enough to achieve the superiority of the branched polymers.The complex interaction mechanism between the host and guest is not throughly studied,and the structure-perofrmance relationship should be further determined.In this thesis,different aryl substituted maleimides and polyfluorene were chosen as the yellow-light emitting guest and blue light-emitting host,respectively.By introducing the guest on the core,or the side-chain of the arm,a series of single-core and dual-core star-shape,even hyper-branched single white light-emitting polymers were obtained.The photophysics properties and the relationship between the structure and performance of these polymers were discussed.Both the quatumn yield of the host and the protecting effect of the guest were improved with the increasing of polymer branch-content.When applied in white light-emitting diodes fabricated by solution processing method,DC-F03 based device exhibites the efficiency of 17.4 cd/A,which is the best efficiency of the device with the same device configuration.The above results show that maleimide combing with the branched structure polyfluorene is useful strategy to fulfill the high efficient white light-emitting.Delicate molecular design can ensure an efficient energy transferring from the host to the guest,eliminate the intermolecular interation and improve the utilization of the excitons. |
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