Synthesis And Characterization Of TADF Hyper-Structured Molecules By Binding Triazine-containing Emitting Units And Host Units Into Calix[4]resorcinarene Core

Thermally Activated Delayed Fluorescence（TADF）material can reach almost100%internal quantum efficiency（IQE）via a reverse intersystem crossing mechanism（RISC）.The noble metal-free TADF emitter have the similar external quantum efficiency（EQE）with that of phosphorescent emitter,which make them be a key factor for the future organic light-emitting diodes（OLEDs）with low-cost and high-efficiency.Solution-processed OLEDs are considered to be the mainstream direction for the development of large-size and flexible flat-panel display technologies in the future due to the advantage of large-area production.Currently,the reported solution-processable TADF light-emitting materials are linear polymeric and dendrimeric TADF materials.The linear TADF polymers have the drawbacks of ambiguous structure and poor reproducibility.As for TADF dendrimers,the molar ratio of TADF units and the host units is restricted by the number of active sites on the TADF moieties.Therefore,it is essential to develop a new strategy to compensate for the defects of linear polymeric and dendrimeric TADF light-emitting materials.In this thesis,a series of hyper-structured molecular（HSM）TADF emitters and a series of hole-transporting materials were designed and synthesized,respectively,in which two functional compounds with different molar ratio were bound together into a CRA core through click reactions.The cheimical structures and properties of intermediates and targets were characterized by¹H NMR,MALDI-TOF MS,FT-IR,EA,DSC,TGA,XRD,AFM,UV-Vis,PL,and CV,etc.Spin-coating these target compounds as emitting layer（EML）or hole-transporting layer（HTL）,OLEDs device were fabricated and measured.Part 1,synthesis and characterization of CRA-PXZ-Trz_（X）-m CP_（100-X）“self-host”HSM light-emitting materials.First,the azide-containing functional compounds PXZ-Trz-N₃ and m CP-N₃ and the inactive core CRA-Alkyne were synthesized.Then,a series of“self-host”HSM TADF materials,CRA-PXZ-Trz_（X）-m CP_（100-X）（X=0,12.5,25,50,75,87.5 or 100,here X represents the percent of PXZ-Trz-N₃ among the added azide-containing functional compounds）were prepared by alkyne-azide click reaction between the alkyne groups of CRA-Alkyne and the azide groups of PXZ-Trz-N₃ and m CP-N₃.¹H NMR,MALDI-TOF MS,FT-IR and EA results indicated the target products were successfully synthesized.DSC showed that the target products have good thermal stability with the glass transition temperatures（T_g）higher than 135°C.AFM showed that the target products have good film-forming properties.The transient PL decay spectra showed that the delayed fluorescence（DF）lifetime of the target products are in the range of 0.49μs～0.76μs and the proportion of DF in total florescence are in the range of 23%～35%.An non-doped OLED device was fabricated by spin-coating CRA-PXZ-Trz_（87.5）-m CP_（12.5）as EML,the obtained device showed a maximum EQE of 16.7%,maximum luminance of 1517 cd/m²,and maximum current efficiency of 50.1 cd/A.Part 2,synthesis and characterization of CRA-TPA_（X）-m CP_（100-X）HSM hole-transporting materials.First,the azide-containing functional compound TPA-N₃ was synthesized.Then,a series of HSM hole transporting materials,CRA-TPA_（X）-m CP_（100-X）（X=0,50,75 or 100,here X represents the percent of TPA-N₃ among the added azide-containing functional compounds）were prepared by alkyne-azide click reaction between the alkyne groups of CRA-Alkyne and the azide groups of TPA-N₃ and m CP-N₃.¹H NMR,MALDI-TOF MS,FT-IR and EA results indicated the target products were successfully synthesized.DSC showed that the target product have good thermal stability with the glass transition temperatures（T_g）higher than 132°C.AFM showed that the target products have good film-forming property.An OLED device was fabricated by spin-coating CRA-TPA_（75）-m CP_（25）as HTL and 4Cz IPN:CBP as EML,the obtained device showed a maximum luminance of 10370 cd/m²,and maximum current efficiency of 21.4 cd/A.Part 3,synthesis and characterization of CRA-COO-PXZ-Trz HSM light-emitting materials.First,the hydroxy-containing functional compounds PXZ-Trz-（CH₂）₆-OH was synthesized.Then,CRA-COO-PXZ-Trz was synthesized via esterification reaction between the hydroxyl groups of PXZ-Trz-（CH₂）₆-OH and the carboxylic acid groups of CRA-COOH.¹H NMR,MALDI-TOF MS,FT-IR and EA results indicated the target product was successfully synthesized,and the introduction degree of functional groups to CRA core is about 74%.An non-doped OLED device was fabricated by spin coating CRA-COO-PXZ-Trz as EML,the obtained device showed a maximum luminance of 871.2 cd/m²,and maximum current efficiency of 2.9cd/A.