Electric field redistribution in light-emitting devices: Transient electroluminescence and time-of-flight studies

Light-emitting devices based on Langmuir-Blodgett films of a porphyrin derivative have been fabricated. In transient electroluminescence (EL) studies, we have observed two components: an instantaneous part and a peak part consisting of a linear rise followed by an exponential decay to a constant level. The time evolution of EL has been explained in terms of intrinsically accumulated charges and hole-induced electric field redistribution. This field redistribution has further been studied by integral mode time-of-flight technique during and after the application of voltage pulse.