| With the development of society,people higher requirements for lighting and display carriers,and Organic Light Emitting Diode(OLED)have achieved unprecedented development.We synthesized three kinds of organic blue materials LDT1,LDT2 and LDT3 on the side chain of oligo-p-phenylene modified alkyl side chain,and studied the influence of side chain on the light-emitting properties of organic light-emitting materials.It is found that the solution processing quality of the material is significantly improved,and the absorption and emission spectra of the material and the device and the energy of HOMO and LUMO are similar.The maximum external quantum efficiency(EQE)of their solution processing devices are1.24%,1.64%,and 1.24%,respectively.The results show that modification of small molecular blue light materials by alkyl side chains can adjust their solubility without affecting other established advantages,including chemical conformation,physical parameters,and device performance.As one of the important factors to adjust the performance of OLED devices,the study of charge transport in the devices is very important.We introduced single molecule conductance measurement(SMCM)technology to analyze the charge transport behavior of three newly synthesized materials CN-TPA,DCN-TPA and TCN-TPA on the surface of Au and Pt.Experiments have found that after modifying the electron-withdrawing side chains to the core light-emitting unit,they can adjust their charge transport ability across the metal-molecule interface.I-V experiments show that the decrease in conductivity between molecules is due to the decrease in metal-molecule coupling.The internal charge transfer of molecules is verified by spectroscopic analysis,electrochemical analysis and density functional theory(DFT)simulation.These findings have guiding significance for designing new material structures,regulating the quality of device solution processing and the balance of carrier transport. |
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