Preparation Of Long-Lived And Tunable Polymer-Based Luminescence Materials,and Research Of UV Irradiation-Dependent Properties

Room temperature phosphorescent materials is a research hots-pot in the field of luminescent materials in recent years.Because of their unique luminescence properties,those materials have shown broad potential in the fields of optoelectronic devices,biological imaging,chemical sensing,and information anti-counterfeiting application.The polymer-based room temperature phosphorescent material can not only continue to emit persistent afterglow after ceased excitation source,but also possess excellent mechanical productivity and high ductility properties.Therefore,it is significant to develop of long emission lifetime,dynamical tunable,large-area prepared polymer-based room temperature phosphorescent materials.Based on the strategy of developing room temperature phosphor materials with long life and high quantum yield by doping and co-polymerization at home and abroad,this paper,focusing on the existing problems of polymer-based room temperature phosphor materials.A series of functional room temperature phosphorescence materials are developed from different perspectives,such as exploring new organic phosphor molecules and new polymer matrix.Furthermore,their photophysical properties have been systematically characterized,and explore its mechanism and applications.In summary,this main content of this paper includes the following three parts:Firstly,we developed a polymer-based room temperature phosphorescent material based on eight vanilla derivatives,include Methyl-vanillate.Due to the strong mutual hydrogen bonding between vanilla derivative and polyvinyl alcohol(PVA)matrix,the rigid environment formed and the non-radiative transition of the phosphors be greatly suppressed.In the room temperature conditions,those doped film of eight vanilla-PVA exhibits ultra-long room temperature phosphorescence emission after 254 nm ultraviolet excitation.Among them,the phosphorescence lifetime of methyl vanillate(M1)reach to363.8 ms,phosphorescence quantum yield is 6.72%,and the long afterglow lifetime up to7 s.At the same time,Methyl-syringate(M2)exhibits a unique green afterglow emission after the molecular structure be designed.It is significant that when the dopant solution of vanilla series phosphor and PVA is used as anti-counterfeiting ink,the afterglow emission time of the same dopant solution on different paper substrates is different.The afterglow emission time on Dorian paper is more than 5 s,while on offset paper it is only 1.5 s.Importantly,the anti-counterfeiting information not only exhibits high stable phosphorescence emission under atmospheric conditions,but also maintains reproducible characteristic of heating/cooling dynamic cycling,the number of cycles is as high as 50times.Secondly,at present,many room temperature phosphorescent materials are realized through crystal engineer strategy,but crystals cannot be widely used in practical applications due to the lack of processability and the crystal size always small,it couldn't be widely used in commercial products.After designed phosphorescent molecular structure of 3,6-diphenyl-9H-carbazole(DPCz),the doped film exhibits a very long-lived phosphorescence lifetime up to 2044 ms.Without encapsulated at room temperature condition,the afterglow emission lifetime is more than 20 s.At the same time,the7H-dibenzo[c,g]carbazole(DBCz)doped film showed a brightness up to 158.4 mcd/m~2after ceasing the ultraviolet excitation.Combined with experimental results,the ultra-long room temperature phosphorescence emission is due to the combined effect of hydrogen bonding and co-assembly effects.Concretely,at the first,the rigid hydrogen bond network formed between the phosphor and the polymer matrix.At the second,co-assembly effect formed between planer phosphors molecular and polymer chain.Both of the two effects are conducive to the formation of a strong rigid environment,which not only effectively suppresses the non-radiative transition,but also prevents the quenching of triplet excitons by oxygen and water molecules.These polymer-based room temperature phosphorescent materials not only have photophysical properties such as long phosphorescence lifetime and high phosphorescence quantum yield,but also have excellent mechanical properties such as machinability,flexibility and transparency of amorphous polymers.Because of these properties,these polymer phosphorescent systems exhibit extremely high mechanical flexibility and transparency in large-area fabrication of various complex 3D geometries without any cracks.Furthermore,a series of afterglow LED arrays can be further applied.Thirdly,room temperature phosphorescence materials with long lifetime and dynamic tunable properties have great potential in wildly applications.However,because of the unclear design strategy and the triplet excitons is highly sensitive to environment conditions,photophysical properties of most reported phosphorescent materials cannot be adjusted.After doped 4,4-dihydroxydiphenylsulfone(SDP)and another similar organic molecular with PVA matrix,a series of ultraviolet irradiation-dependent room temperature phosphorescence systems have been developed.After continuous irradiated by 254 nm and40u W/cm~2ultraviolet source for 45 minutes,eight kind of polymer-doped films showed obvious radiation-enhanced green or yellow phosphorescence emission.Without irradiation,SDP doped film has no afterglow emission.After 45 min irradiation,the SDP-doped film showed obvious green phosphorescence emission,and the phosphorescence lifetime(?_p)from 58.03 ms to 828.81 ms,14 times increased.Meanwhile,the phosphorescence quantum yield(?_p)from 2.06%to 4.96%,2.4 times increased.Based on the results of experiments and theoretical calculations,it is proved that the hydrogen bonding and those new cross-linking bonds has greatly suppressed the non-radiative transition in the doped systems,and exhibit unique long-lived room temperature phosphorescence.Combined with the photophysical behavior of those irradiation stimuli-responsive materials,it shows great potential in multi-color screen printing,high-level information encryption and display applications.