The use of electrical pulses to study the physics of bilayer organic light-emitting diodes

We present detailed experimental and theoretical analysis for both constant-wave and pulsed excitation for a variety of real bilayer organic light-emitting diodes (LEDs). We find from experiment and simulation that the recombination zone may be moved about the polymer-polymer heterojunction as a function of the applied voltage. We suggest a method for spectrally resolving the emission of both polymers of a bilayer LED as a function of time, and show that these results are in good agreement with time-dependent simulation results. The simulation model takes into account both the discontinuities in energy levels and mobilities across the polymer-polymer heterojunction. (C) 2004 American Institute of Physics.