Synthesis Of Novel Carrier Transport Materials And Their Device Performance

Organic light-emitting devices?OLEDs?play an important role in the field of next-generation lighting and flat panel displays.At present,the research on OLED mainly focuses on two aspects:materials and device structure.The research on luminescent materials has made great progress.However,the research on charge transport materials is relatively lagging.Charge transport materials with high carrier mobility and good morphological stability are of great significance for improving the comprehensiveness of organic light-emitting devices.In order to improve the efficiency and reduce the power consumption of the device,a series of electron transport materials and hole transport materials were designed and synthesized.We are successfully prepared OLEDs with high brightness,high efficiency,simple structure and good stability.The main research contents are as follows:1.The novel hole transport materials TPA-DMAC,TPA-PXZ and TPB-PXZ were designed and synthesized to characterize the thermal stability,photophysical properties and electrochemical properties.The triplet energy levels of TPA-DMAC?TPA-PXZ and TPB-PXZ are 2.93 eV,2.71 eV and 2.53 eV,respectively,and the HOMO and LUMO levels are-5.40 eV/-1.96 eV,-5.26 eV/-2.0 eV and-5.33 eV/-2.25 eV,respectively.The higher HOMO levels of the three compounds facilitate the injection of holes from the anode.The LUMO energy level is also relatively high,which can block the transmission of electrons.We prepared a single carrier device with the structure of ITO/MoO₃/HTL/MoO₃/Al,measured the carrier mobility of three hole transport materials,and applied these materials to a green light-emitting device using CBP:Ir?PPy?₂acac as a light-emitting layer.The results show that the devices based on the three materials have high current efficiency,high power efficiency and external quantum efficiency,and the external quantum efficiency of TPA-DMAC?TPA-PXZ and TPB-PXZ They were20.5%,20.0%,20.2%,respectively.2.The novel electron transport materials TRZ-1SO₂,TRZ-2SO₂ and TRZ-3SO₂were designed and synthesized,and the properties of the compounds were characterized.The triplet energy levels of TRZ-1SO₂,TRZ-2SO₂ and TRZ-3SO₂ are 2.62 eV,2.61 eV and 2.56 eV,respectively,and the HOMO and LUMO levels are-7.21 eV/-3.38 eV,-7.46 eV/-3.58 eV,-7.47 eV/-3.74 eV respectively.Studies have shown that triazine-based derivatives have higher T₁ state energy levels and deeper HOMO energy levels,which can be used as hole blocking materials.In addition,we measured the electron mobility of three materials and prepared a green light device with CBP:Ir?PPy?₂acac as the light-emitting layer.The results show that the maximum current efficiency and power efficiency of TRZ-1SO₂ and TRZ-2SO₂-based devices reached 88.6 cd A^-1/106lm W^-1 and 85.9 cd A^-1/108 lm W^-1,respectively.The maximum external quantum efficiencies of three devices were 23.2%,22.7%and 17.3%,respectively.Further research on the function of the electron transport materials was carried out in the OLED of the exciplex mechanism.The results show that the starting voltage of three devices is2.3 eV,and the maximum external quantum efficiency of TRZ-3SO₂-based devices reached 11.1%,indicating that the three materials have great application potential in the exciplex.