Properties of Flexible Phosphorescence Polymer Light Emitting Diodes Coated on Polyethylenenaphthalate Plastic Substrates

Abstract

Flexible phosphorescence polymer light emitting diodes (PhPLEDs) with PEN/ITO/PEDOT:PSS/ PVK:Ir(ppy)(3)/TPBI/LiF/Al structure were fabricated to investigate the effects of Ir(ppy)(3) doping concentrations on the optical and electrical properties of the devices. PVK and Ir(ppy)(3) conjugated polymers as host and guest materials in the emission layer were spun coated at various concentrations of Ir(ppy)(3) ranging from 2.0 to 8.0 vol%. As the concentration of Ir(ppy)(3) increased from 2.0 to 6.0 vol% the electrical and optical properties of the flexible PhPLEDs were improved clearly. Maximum luminance and current density were obtained for a PhPLED with an Ir(ppy)(3) concentration of 6.0 vol%, with 6815 cd/m(2) and 393 mA/cm(2) at 9 V. The current efficiency tends to increase with the Ir(ppy)(3) concentration, because of the formation of the excitons required to emit light.