Study On The Synthesis Of Zero-dimensional Halide Phosphorescent Materials And The Preparation Of Flexible Phosphorescent Film By Printing

The research of zero-dimensional（0D）halide phosphorescent materials have been progressed largely in last ten years,widely used and played important roles in optical sensing,biological imaging,anti-counterfeiting and information storage fields.A series of phosphorescent materials with high efficiency have been developed,but the exact mechanism of phosphorescence is still an unsolved problem.Moreover,the application of Room Temperature Phosphorescence（RTP）is still limited,It needs to be used in an environment without water or oxygen,Its development is greatly limited,and the phosphorescent lifetime is only microseconds and milliseconds.Current studies on phosphorescence properties have shown that it is the intramolecular energy level transitions in the crystal lead to efficient phosphorescence.In the crystalline state,intermolecular interactions restrict molecular vibration,producing bright RTP under ultraviolet light.The formation of crystals is crucial for the protection of triplet exciton,avoiding internal conversion or oxygen caused RTP quenching.And introducing bromine and iodine can increase the efficiency of intersystem crossing due the heave atom effect.In addition to the transition change caused by the halogen,hydrogen bonding is also one of the sources for RTP regulation.However,it is difficult to study RTP materials due to their poor spin-orbit coupling and some environmental factors,among other factors.In order to solve the above problems,in this dissertation,tetraphenyl phosphonium cation with efficient triplet excitons,is selected because of its huge C₃symmetric molecular structure can effectively resist molecular vibration and rotation caused by temperature rise.By introducing different counter anionic groups,centimeter-grade single crystal materials with RTP properties were cultivated.And further investigation on new zero-dimensional halide phosphorescent materials with the dehydration study and heavy atoms doping,revealed that the intermolecular interaction,the heavy atom effect,the hydrogen bond together with other factors have a very important impact on phosphorescence properties.It is found that the heavy atom effect has a great influence on the intersystem crossing and the phosphorescence yield is greatly improved due to this effect on the intersystem crossing coefficient.It is also found that the hydrogen bond formed between water and organic molecules also has a positive effect on the phosphorescence performance.Finally,using inkjet printing technology,the 0D phosphorescent materials have been successfully printed on flexible film,for anti-counterfeiting display.The main works of this dissertation include the following three parts:（1）The synthesis and characterization of seconds-long life green new type of 0D halide phosphorescent materials:titanium tetraphenylphosphonium hexafluoride dihydrate and zirconium tetraphenium hexafluoride dihydrate were synthesized using a simple hydrothermal method and can produce phosphorescent green luminescence up to 6 seconds.A series of analyses on spectra and the crystal structure of these two materials show that stable crystal structure and efficient intramolecular energy transition are essential conditions for continuous phosphorescence generation.（2）Study on heavy atom（Br）ion doping:With heavy atoms（Br）ions doping,it is confirmed that the heavy atom effect has great influence on the phosphorescence,mainly through its influence on intersystem crossing between the single and triplet states,hence improving the population number of triplet exciton.Meanwhile,phosphorescence quantum yield can be further controlled by adjusting the Br ion doping ratio,enabling the phosphorescence quantum yield adjusteable.In addition,crystal dehydration experiments revealed a positive effect of water molecules on the rigid crystal structure,mainly through hydrogen bonding with upper and lower organic molecules,which stabilized the crystal structure,weakened molecular vibration,inhibited the triplet exciton non-radiative transition,and enhanced the phosphorescence lifetime.（3）Fabrication of anti-counterfeiting film with new 0D halides phosphorescent materials:A novel zero-dimensional halide phosphorescent material was used to prepare the inks for inkjet printing,which were printed on different substrates by inkjet printer,and anti-counterfeiting phosphorescent film was prepared.The inhibition effect of binary solvent ink on coffee ring phenomenon was studied,and show the anti-counterfeiting function,has important significance to the micro anti-counterfeiting field.