Dry Preparation And Research Of Phosphorescent OLED

At present,research in the field of organic light-emitting diode（OLED）is developing rapidly,but OLEDs still have some problems,including efficiency roll-off and high operating voltage.How to solve these problems has become a research hotspot.In this thesis,a series of green phosphorescent devices were prepared by dry process.The electroluminescence（EL）performances of devices were studied by optimizing the doped concentration of emitting materials and the thickness of functional layers.The main work are as follows:1.Ir（mppy）₃ was selected as the emitting material,and mCP was used as the host material to prepare single light-emitting layer（EML）device of Ir（mppy）₃:mCP system.The effect of the doping concentration of Ir（mppy）₃ and the thickness of the mCP for OLED performances was studied.Finally,the device with a doped concentration of 8 wt%has the best performance,and its current efficiency roll-off is 5%at a brightness of 1000cd/m².2.TNT1 was selected as the emitting material,and single-and double-EML（s）system OLED were prepared with 26DCzPPy and TcTa/26DCzPPy as the host materials,respectively.The effect of TNT1 doping concentration on device performance was studied.By comparing,the double-EMLs OLED has better EL performance.Eventually,a double-EMLs device based on doped concentration of 10 wt%had the best performance,with maximum current efficiency of 37.15 cd/A.Even at the brightness of 2000 cd/m²,the current efficiency as high as 35.53 cd/A,the current efficiency roll-off is only 4%.3.Ir（mppy）₃ was selected as the emitting material and mCP/CzSi were used as the host materials to prepare double-EMLs OLED.By optimizing the doped concentration of Ir（mppy）₃,a high-performance device was obtained with a maximum power efficiency of68.36 lm/W,and its turn-on voltage is only 2.8 V.4.Ir（mppy）₃ was selected as the emitting material,BUPH1 and TcTa were used as the host materials.A series of devices were designed and fabricated with different EML structures.With the doped concentration of Ir（mppy）₃ and thickness of TcTa increase,the power efficiency improves firstly to the maximum and then decreases gradually.And,the device,doped concentration of 10 wt%and TcTa thickness of 8 nm,achieved the highest power efficiency of 111.94 lm/W,moreover its turn-on voltage is only 2.3 V.