Preparation and Characterization of Green Polymer Light Emitting Diodes with Silver Nanowires

As next generation large area flexible displays, polymer light emitting diodes (PLEDs) have received much attention from many researchers. The silver nano-wires (AgNWs) of PLEDs have good characteristics in terms of the electrical, optical, and thermal properties. In this study, green emitting PLEDs were prepared by embedding AgNWs into a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) hole transport layer (HTL) and/or an emission layer (EML) for improvement of light efficiency. We prepared the PLEDs using spin coating method with the structure of glass/ITO/PEDOT:PSS + AgNWs/-PVK:Ir(ppy)(3) + (AgNWs)/TPBi/LiF/Al. To find out the optimized concentration of Ag-NWs, AgNWs were blended at amounts ranging from 0.5 to 5.0 wt% with the HTL. The largest luminance and external quantum efficiency (EQE) was thus obtained for the PLED sample with an AgNW concentration of 1.0 wt%. The maximum luminance and EQE were about 20520 cd/m(2) and 6.40%, respectively. In addition, AgNWs were embedded into the EML and HTL + EML of the devices, and the EQE and luminance were compared among the prepared samples. The luminance and quantum efficiency decreased when AgNWs were embedded into the EML, in the combined EML and HTL, suggesting the interference of the carrier recombination at EML.