Optoelectronic properties of poly(fluorene) co-polymer light-emitting devices on a plastic substrate

The optoelectronic properties of red, green, and blue poly(fluorene) co-polymer light-emitting devices (PLEDs) on a plastic substrate having a multi-layered structure with water vapor and oxygen transmission rates of less than 10(-5) g/cm(2)-day-atm and 10-7 cc/cm(2)-day-atm, respectively, is reported. A semitransparent thin metal multi-layer (i.e., Au/Ag/Au or Ag/Au/Ag) is placed between the plastic substrate and the ITO coating, achieving a low sheet resistance of 12-13 Omega/square and an adequate optical transmission greater than 75%. A wider color gamut and a maximum emission efficiency of 0.7, 10, and 1.7 cd/A for red, green, and blue PLEDs, respectively, was obtained. Finally, a simple equivalent-circuit model was used to simulate the current-density-voltage characteristics of PLEDs.