Search results for "Electron-hole recombination"
showing 3 items of 3 documents
Impedance of space-charge-limited currents in organic light-emitting diodes with double injection and strong recombination
2006
The impedance model for a one-carrier space-charge-limited (SCL) current has been applied to explain some experimental features of double carrier organic light-emitting diodes. We report the analytical model of impedance of bipolar drift transport in SCL regime in the limit of infinite recombination. In this limit the ac impedance function is identical to that of a single carrier device, with a transit time modified by the sum of mobilities for electrons and holes, μn+μp. The static capacitance C(ω→0) is a factor of ¾ lower than the geometric capacitance, as observed for single carrier devices, but it is shifted to higher frequencies. It follows that impedance measurements in the dual-carri…
Oscillator strength reduction induced by external electric fields in self-assembled quantum dots and rings
2007
We have carried out continuous wave and time resolved photoluminescence experiments in self-assembled In(Ga)As quantum dots and quantum rings embedded in field effect structure devices. In both kinds of nanostructures, we find a noticeable increase of the exciton radiative lifetime with the external voltage bias that must be attributed to the field-induced polarizability of the confined electron hole pair. The interplay between the exciton radiative recombination and the electronic carrier tunneling in the presence of a stationary electric field is therefore investigated and compared with a numerical calculation based on the effective mass approximation.
Millisecond radiative recombination in poly(phenylene vinylene)-based light-emitting diodes from transient electroluminescence
2007
The current and electroluminescence transient responses of standard poly phenylene vinylene -based light-emitting devices have been investigated. The electroluminescence time response is longer milliseconds scale than the current switch-off time by more than one order of magnitude, in the case of small area devices 0.1 cm2 . For large area devices 6 cm2 the electroluminescence decay time decreases from 1.45 ms to 100 s with increasing bias voltage. The fast current decay limits the electroluminescence decay at higher voltages. Several approaches are discussed to interpret the observed slow decrease of electroluminescence after turning off the bias. One relies upon the Langevin-type bimolecu…