Effect Of Coupled Structures Cathode And Thin Organic Layer On The Performance Of OLED

As a new generation's panel display technology,the organic light-emitting devices (OLEDs) have attracted a lot of attention due to its prominent technology and advantages for giant market application prospect.For a typical OLED,the number of hole and electron balanced is important to the performance.The enhancements of electron injecting and transporting and the suppressants of hole injecting and transporting are efficient paths to improve the performance of OLEDs.In this thesis,the following work has been done:1.To manufacture a coupled structure of Al/Ni cathode,the performance of OLEDs with coupled structures is investigated.The thicknesses of Al and Ni have been optimized in the coupled structure cathode.The highest brightness of 8448 cd/m~2 is obtained for the device with LiF/Al/Ni cathode at a voltage of 18 V.At the current density of 200 mA/cm~2 the power efficiency reaches 1.82 cd/A,which is 1.3 times higher than that of the device with LiF/Al,is obtained.Results show that the coupled structure cathode enhances the electron injection compared to the only-Al cathode,and the suggested mechanism is proposed in the thesis.2.To use three hole blocking materials BCP,PBD and AlQ inserted at the interface of ITO/NPB and in the NPB layer.Results show that the performance of device with BCP as the hole buffer layer is the best.When the BCP thin buffer layer is inserted in the NPB layer,the device got a brightness of 1184 cd/m~2,at the voltage of 16V.At the voltage of 12V,the current efficiency reached 1.33 cd / A.The effect of hole blocking layers and their positions in the devices on the properties of OLEDs was investigated.