HIGH-BRIGHTNESS AND EFFICIENCY BLUE-LIGHT-EMITTING POLYMER DIODES

Efficient blue electroluminescence, peaked at 436 nm, is demonstrated from polymer light-emitting diodes operating at high brightness. A dio ctyl-substituted polyfluorene was used as the emissive layer in combin ation with a polymeric triphenyldiamine hole transport layer. The lumi nance reaches 600 cd/m(2) at a current density of 150 mA/cm(2) for a b ias voltage of 20 V, corresponding to an efficiency of 0.25 cd/A and a luminosity of 0.04 lm/W. These values are optimized at a critical emi ssive layer thickness. (C) 1998 American Institute of Physics.