Design And Synthesis Of Multidimensional Iridium Complexes With In Vivo Photoelectric Functionality

Electrophosphorescence materials and devices are one of the focuses for electroluminescence technology,with the feature of 100%exicton harvesting for energy conversation and environmental protection.Ir³⁺complexes are one of the most important phosphors with the advantages in stable room-temperature phosphorescence,high photoluminescence quantum yield and short lifetime,therefore realizing the favorable electroluminescence performance.However,the strong intermolecular interactions induce the serious triplet-triplet annihilation and concentration quenching for phosphorescent complexes.To reduce the intermolecular interaction,host-dopant doping structures are widely adopted in emitting layer to reduce the quenching effects on device efficiencies,however,accompanied by worsened operation stability due to phase separation,etc.Therefore,in recent years,a series of electrophosphorescence polymers and dendrimers were developed as the solid examples of host-dopant integration strategy.In this thesis,on the basis of charge transfer-aliphatic chain(CT-AC)mixed modification strategy,through introducing host-featured groups at multiple positions,Ir³⁺complexes with multi-dimensional host modification were constructed,in which phenylbenzimidaole was used as ligand substituted with three carbaole or triphenylphosphine oxide groups on phenyl and N-position of imidazole to further construct Ir³⁺complexes with nine peripheral groups.The incorporation of carbazole and triphenylphosphine oxide groups can not only improve the film formability,effectively suppress the intermolecular interactions and improve the emissive performance,but also optimize the carrier injection and transportation in the complex films.Simultaneously,in virtue of the separation effect of aliphatic chains,the peripheral groups can not influence the emissive colors of the Ir³⁺cores,establishing the basis of selective modulation the encapsulation effect on cores through tuning the density and orientation positions of the peripheral groups.Among them,Ir(34NTCz PBI)₃ with the most uniformly dispersed nine carbazole groups showed the favorable electroluminescence performance.Through spin-coating fabrication,the bilayer nondoped devices using Ir(34NTCz PBI)₃ achieved the maximum external quantum efficiency of 8.3%and the near-zero EQE roll-off at 1000 cd m^-2,which demonstrated the superiority of charge transfer-aliphatic chain(CT-AC)mixed modification strategy on constructing high-efficiency small-molecular electrophosphorescence complexes.