Impedance of space-charge-limited currents in organic light-emitting diodes with double injection and strong recombination

Abstract

The impedance model for a one-carrier space-charge-limited ͑SCL͒ 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, n + p . The static capacitance C͑ → 0͒ is a factor of 3 4 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-carrier organic diodes with strong recombination provide the combination of n + p . For the mobilities of the different carriers to be determined separately, additional information is required.

Operating Modes of Sandwiched Light‐Emitting Electrochemical Cells

“…These are rather standard features of physical models for OLEDs. [ 33 ] Using an analytic formulation of this LEC model, described in the Supporting Information (SI), we derive a potential distribution (Figure 3 b) quite similar to that obtained using Kelvinprobe measurements as reported by Matyba et al [ 18 ] We have thus demonstrated that the LECs described here show a transition from an injection-limited state to a state in which good and balanced injection occurs. After this transition a further increase in current occurs, which implies a reduction in the thickness of the neutral region due to a continuous growth of the doped layers.…”

Charge transport characterization in a squaraine-based photodetector by means of admittance spectroscopy

“…where C 1 is a practically constant contribution, including eventual space charge effects, as reported from SCLC model [19,26,32]. Fig.…”

Giant, Anomalous Piezoimpedance in Silicon-on-insulator

“…3, 4 and 5. More recently, similar sets of equations have been used to model charge leakage in organic materials but in these cases simplifying assumptions are still made; in some cases the trapping and re-emission expressions are not explicitly consistent with the non-steady-state capture rates given in the SRH model [48,49], whereas in others recombination is assumed to be infinitely fast [60]. In short, the solution of Eqns.…”