Design,Synthesis And Property Investigations Of Exciplex-Based Organic Afterglow Materials

With the characteristics of easy structure modification,flexibility,good biocompatibility,and extensive matrix compatibility,organic ultralong afterglow materials have been widely used in the fields of information encryption and anti-counterfeiting,data display,biological imaging,and so on.It is one of the frontier research hotspots in the field of organic optoelectronics.Because of its advantages of long luminescence duration and easy preparation,the exciplex has become a new choice for the development of long afterglow materials in recent years,and has attracted extensive attention from researchers.In the exciplex system,acceptor material choice is very important,not only need to form a rigid environment to isolate water oxygen,restrain the non-radiative transition,but also need to have effective carrier transmission ability,can give donor with an effective charge separation of the state,so as to realize the afterglow luminescence of long duration.But,it is still a challenge to develop excellent acceptor materials to achieve high performance of exciplex with long afterglow.At the same time,the existing exciplex materials are relatively simple,and more kinds of material systems need to be developed to achieve diversified exciplex.Based on this,this paper focused on the development of electron acceptor materials,designed and prepared a series of high performance exciplex,at the same time,the introduction of chiral units also realized the circular polarization afterglow with extremely long duration.Specific research contents are as follows:（1）In order to develop more acceptor molecules capable of achieving high performance exciplexes,a series of acceptor molecules were designed and synthesized phosphine-oxide-based structural units in this chapter.A series of exciplex systems have been successfully prepared by heating and bulking the donor molecules TMB at a certain molar ratio.Through a series of photophysical tests and characterization,it is found that the quantum efficiency of the system is the lowest,and the free radical decay rate is the slowest,which are the reasons for the realization of ultra-long afterglow,the long persistent time of the system can reach 3h.The high-performance green afterglow is finally achieved due to the double emission of the exciplex and the donor phosphorescence.Benefit from the excellent luminescence performance of the system,it was innovatively applied in light-emitting diode devices and successfully realized the afterglow light-emitting diode lighting device,which opened up a new direction for the application of exciplex.（2）In order to solve the problem that the existing circularly polarized organic long afterglow materials have short luminescence duration,two circularly polarized exciplex long afterglow materials with extremely long durations were successfully prepared in this chapter by introducing the chiral unit into the donor molecules,and then bulking and melting the chiral donor and acceptor molecules PPT.Due to the unique ultra-long luminescence characteristic of exciplex,the exciton can be continuously transferred to the triplet state of the circularly polarized donor through energy transfer,and the ultralong circular polarization afterglow can be finally realized.Through the characterization of circularly polarized luminescence spectrum,the characteristics of circularly polarized luminescence of the material are confirmed.The luminescence dissymmetry factor can reach 1.4×10^-3,and the duration time can reach about 90 min.The work in this chapter provides an idea for constructing circularly polarized long afterglow materials with extremely long durations and greatly expands the diversity of materials with long afterglow in exciplex.