Synthesis And Properties Of Organic Single Molecule White-emitting Materials Based On Phthalimide

In recent years,organic single-molecule white-emitting materials have been a research hotspot in the field of luminescent materials due to their broad application prospects in the fields of lighting,display,molecular sensors and probes,etc.In this master's thesis,the research status of organic single-molecule white-emitting materials and their applications in single-dopant white organic light-emitting devices(WOLEDs)are systematically reviewed.Aiming at the key scientific issues of organic single-molecule white-emitting materials,such as few molecular systems,difficult molecular design and low luminous efficiency,etc.We carried out the research of novel organic single-molecule white-emitting materials based on phthalimide.The main research work and results are as follows:(1)A series of organic single molecule luminescent materials CNPL-PTZ,CNPL-PXZ and CNPL-tDPA with asymmetric D-A-?-A'structure were designed and synthesized.The related molecular structure is characterized by the introduction of different substituents at the 4-position of phthalimide.CNPL PTZ and CNPL-tDPA have obvious aggregation induced luminescence(AIE)and aggregation induced luminescence enhancement(AIEE),respectively.By adjusting the solution concentration,solution polarity and doped film concentration,the compound CNPL-PTZ can effectively achieve white light emission.In addition,CNPL-PTZ has the characteristic of multistimulus response mechanochromic luminescence(MCL).The CNPL-PTZ based single molecule doping device achieves warm white light emission,and the maximum external quantum efficiency(EQE_max)is 0.41%.(2)A series of D-A-?-D'type single molecule luminescent materials CzPL-PTZ?CzPL-PXZ?CzPL-tDPA and CzPL-tTPA with asymmetric double donor units were designed and synthesized.The effect of carbazole group modified on the N-position of phthalimide on the photoelectric properties was studied.CzPL-PTZ has obvious AIE properties,CzPL-tDPA and CzPL-tTPA have obvious AIEE properties.In addition,CzPL-PTZ can effectively achieve white light emission by adjusting solution concentration,solution polarity and doping film concentration.Compared with CNPL-PTZ,the spectra have a blue shift.Meanwhile,both CzPL-PTZ and CzPL-tDPA have obvious multi stimulus response MCL properties.The EQE_max of CzPL-PTZ,CzPL-tDPA and CzPL-tTPA based single molecule doped evaporated devices are 0.77%,3.52%and 8.14%,respectively.The OLED based on CzPL-PTZ achieves warm white light emission with CIE coordinates of(0.36,0.42).(3)Two kinds of single molecule luminescent materials 3-CzPL-PTZ and 3-CzPL-tDPA with asymmetric D-A-?-D'type structure were designed and synthesized.The influence of phthalimide's 3-position modification on its photoelectric properties was systematically investigated.These materials have rigid structure,so they have good thermal stability.However,due to the excessive distortion of D-A,the orbital overlap of HOMO and LUMO is limited,meanwhile,the interaction is blocked,resulting in almost no luminescence of 3-CzPL-PTZ and weak red shift luminescence of 3-CzPL-tDPA.