Enhancing The Electron Current Of Organic Light Emitting Diodes

Organic light emitting diodes(OLEDs)have attracted tremendous attention across the industrial and scientific fields,due to their appealing merits of high response speed,high contrast,wide view angle,flexibility,and so on,which can meet the customers'increasing requirements.Although small-to medium-sized OLED displays have been commercialized,such as foldable screen for mobile phones,they are still suffering from the problematic issues like high price,image retention,short lifetime,etc.,limiting their larger commercial applications.This thesis makes use of electrically doped thin films to design some novel architectures for OLEDs,in attempt to solve the drawbacks of current OLEDs and thereby push forwards the OLED display technology.The main content of the thesis is as follows.(1)Optimization of inverted organic light emitting diode(IOLED).The performance of organic n-doped layer is related to the n-dopant concentration.The structure of IOLED is optimized by regulating the profile of the n-doping concentration.Compared with conventional n-doped layer of 30 nm 4:1 BCP:Li₂CO₃ or 30 nm 8:1 BCP:Li₂CO₃,10 nm4:1 BCP:Li₂CO₃/10 nm 8:1 BCP:Li₂CO₃/10 nm 4:1 BCP:Li₂CO₃ can reduce the injection loss,conduction loss,and transfer barrier–based interfacial loss,thereby enhancing electron current and luminous performance of IOLED.(2)Optimization of phosphorescent p-i-n OLED.The performance of organic p-doped layer is related to the p-dopant concentration.The structure of p-i-n OLED is optimized by regulating the profile of the p-doping concentration.The combination of 10 nm 2:1CBP:MoO₃ and 20 nm 4:1 CBP:MoO₃ device shows increased current density and efficiency than single 30 nm 4:1 CBP:MoO₃ or 2:1 CBP:MoO₃.(3)Optimization of inverted organic solar cell(OSC).Both CBP:MoO₃ and MoO₃have been used as hole extraction layers in inverted OSCs.When the thickness of hole extraction layer?20 nm,the short-circuit current densities of the inverted devices based on CBP:MoO₃ and MoO₃are almost same,but the novel hole extraction layer of CBP:MoO₃improves fill factor and power conversion efficiency than MoO₃.Regulating the electrical doping concentrations is able to enhance electron current and hole current of p-i-n OLED,therefore,it is of great significance to advance the OLED field.The thesis provides new insights to solve the problems limiting current OLED industry.