Research On Application Of Carbon Quantum Dots In Organic Electroluminescence Devices

In recent years,Organic Light-Emitting Diodes?OLEDs?exhibit a great progress in scientific research and commercial product promotion.This is because OLED combines the advantages of thin-light products,low price of materials,flexible manufacturing and high energy conversion efficiency.The progress of color display technology is the key to the development of OLED.The manufacture of full-color display devices with high purity and high efficiency is a hot research field of organic electroluminescent devices.Methods of achieving full-color display methods are RGB Three-Color Luminescence,Color Conversion and White Light Conversion.However,insufficient of color purity of luminescent materials,short lifetime of luminescent materials and light loss caused by filter films limit the development of OLED practical applications.The quantum confinement effect,particle surface effects and tunneling effects of quantum dots exhibit excellent electrical and optical properties.Applying special properties of quantum dots in OLED devices.We could produce quantum dot OLED devices with excellent photoelectric properties.The main contents of the thesis include:The CQDs were prepared by a microwave-assisted method.Developing yellow-blue dual-emissionhybridWOLEDswhichstructureareITO/m-MTDATA/NPB/MADN:TBPe/CQDs/MADN:Rubrene/BCP/Alq₃/Al.Experimental results exhibit that by embedding CQDs,WOLEDs with a low turn-on voltage of 12 V which is 40%lower than reference devices can be achieved.A maximum luminance 19500 cd/m² is obtained at 19 V of WQOLEDs,which is obviously higher than a maximum luminance 14600 cd/m² of reference devices at 30 V by comparing the optical properties of the two sets of devices.Meanwhile,When the forward voltage is applied to the WQOLEDs devices ranging from14 V to 22 V,the CIE coordinates of WQOLEDs moving to?0.34,0.37?from?0.27,0.29?linearly.WQOLEDs exhibits a strong stable luminous chromaticity modulation effect that is suitable for solid-state lighting applications.This experimental result provides a new idea for the fabrication of OLED devices which could full-color display without color filters.Another contrast experiment has been design.Developing WOLEDs which structure are ITO/m-MTDATA/NPB/MADN:TBPe/CQDs/MADN:Rubrene/BCP/Alq₃/Al.Experimental results exhibit that the turn-on voltage,current density and luminescence brightness of WQOLEDs devices exhibit a significant performance improvement.Meanwhile,as the forward voltage change of the WQOLEDs,the CIE coordinates of devices are stabilized at the same point.In other words,the stability of the luminescent color of WQOLEDs is improved.The excellent electrical performance of WQOLEDs is speculated to be a consequence of multiple exciton generation?MEG?effect of CQDs.Wealsodevelopblue-emissionOLEDswhichstructureareITO/m-MTDATA/NPB/CQDs/MADN:TBPe/BCP/Alq₃/Al,yellow-emission OLEDs which structure are ITO/m-MTDATA/NPB/CQDs/MADN:Rubrene/BCP/Alq₃/Al,red-emission OLEDs which structure are ITO/m-MTDATA/NPB/CQDs/Alq₃:Rubrene:DCJTB/Alq₃/Al and green-emission OLEDs which structure are ITO/m-MTDATA/NPB/CQDs/Alq₃/Al.The experimental results show that CQDs OLED devices are significantly superior to the reference OLED devices in optical and electrical performance except green-emission OLEDs.The Ag-CQDs were prepared by a UV-deoxidized method.Developing WOLEDs which structure are ITO/m-MTDATA/NPB/MADN:TBPe/CQDs/MADN:Rubrene/BCP/Alq₃/Al and Developing WOLEDs which structure are ITO/m-MTDATA/NPB/MADN:TBPe/Ag-CQDs/MADN:Rubrene/BCP/Alq₃/Al.The experimental results show that CQDs WOLEDs devices and Ag-CQDs WOLEDs devices are significantly superior to the reference OLED devices in optical and electrical performance.Ag-CQDs WOLEDs devices exhibit strong stable luminous chromaticity modulation effect than CQDs WOLEDs.This phenomenon is caused by the MEG effect of CQDs and the SPR effect of Ag-CQDs.Experimental results exhibit important reference value for the fabrication of WOLEDs devices which could full-color display.We analyze the failure mechanism of OLED devices from theory and experiments and propose a variety of improvements.Promoting the process of productization of OLED devices.