High-frequency response of polymeric light-emitting diodes

The frequency dependence of alternating-current polymeric light-emitting diodes has been studied. Langmuir-Blodgett (LB) films of poly(3-hexylthiophene) have been used as the active emitting material sandwiched between LB films of emeraldine base polyaniline to form the device. We have shown that by reducing the thickness of the emitting layer using the LB deposition technique, one can increase the high-frequency operating limit of the device. From the -3 dB frequency, we have calculated the carrier mobility in the emitting polymer layer, and compared it with the Poole-Frenkel model. The electroluminescence and photoluminescence spectra have been studied. (C) 1997 American Institute of Physics.