The Study Of The Relationship Between Structure And Performance Of WOLED

White organic light-emitting diodes(WOLEDs)have attracted much attention for high efficiency,wide angle of view,response speed,ultra-thin,light weight,flexibility,and so on.Although the researches of WOLEDs have made some progress,it still needs to explore the working mechanisms of WOLEDs,due to the complex device structures and the complicated influence factors.We have fabricated simplified structure WOLEDs,single light-emitting layer WOLEDs and multiple light-emitting layer WOLED to analyze the influences of material properties,organic layer thickness,the interfacial barriers on the carriers transfer and compound in WOLEDs.Through a series of experiments,we have studied the two luminescent processes which are carriers capture process and energy transfer process.By deeply analyzing the working mechanisms of the devices,we have found the influence factors on efficiency,Von,spectral properties,and so on.This paper is divided into the following parts:1.We have fabricated simplified structure WOLEDs,studied the influence of light emitting layer thickness on carriers transfer and compound by changing the thickness of blue light emitting layer(Tmpypb: Firpic)and orange light emitting layer(CBP: Ir(MPCPPZ)3).The device`s maximum current efficiency could reach 21.3 cd/A,CIE(0.36,0.36),Von 5.5 V.By introducing Tmpypb as electronic transport layer,we optimized the efficiency and Von at the same time,the device` maximum current efficiency could reach 23.59 cd/A,CIE(0.36,0.36),Von 3.3 V.2.We have fabricated multiple light-emitting layer WOLEDs.By using CBP and TCTA as hole transport layer respectively,we studied the influences of interfacial barrier on the carriers transfer.Through using Tmpypb and TCTA as the host of blue light emitting layer respectively,we studied the influences of the carrier transport properties of host materials on exciton compound area.Eventually,we have optimized the device structure Mo O3(5 nm)/ NPB(60 nm)/ TCTA(5 nm)/ CBP: Ir(MPCPPZ)3(2%,10 nm)/ TCTA: Firpic(8%,10 nm)/ Tmpypb(35 nm)/ Cs2CO3(2 nm)/ Al(120 nm).The device` maximum current efficiency could reach 25.25 cd/A,CIE(0.32,0.32),Von 3.5 V.3.We have fabricated single light-emitting layer WOLEDs by using different materials CBP and TCTA as the host of EML.Through the analysis of single electron devices,PL spectrum and a series of experiments,we studied the processes of energy transfer and carrier capture.By changing the hole transport layer,we investigated the influences of the relationship between the host and the hole transport layer on the performance of single light-emitting layer WOLED.The optimized device structure ITO/ MoO3(5 nm)/ CBP(35 nm)/ CBP: Firpic:(PQx D)2Ir(TP)(5%,0.4%,15 nm)/ Tmpypb(35 nm)/ Cs2CO3(2 nm)/ Al(120 nm),The device` maximum current efficiency could reach 38.81 cd/A,Von 3.1 V,CIE(0.32,0.39).