Frequency-dependent electrical response of holes in poly(p-phenylene vinylene)

Simultaneous measurement of electron and hole mobilities in polymer light-emitting diodes

“…From the specific frequency-dependent response the hole mobility could be derived. 9 In the PLED the transit of both electrons and holes can be clearly separated in the frequency domain, yielding the respective carrier mobilities. In contrast to J(V) and TOF, admittance spectroscopy does not suffer from the presence of deep traps, since release rates from deep traps are Ӷ1 s Ϫ1 and, hence, fall out of the frequency window studied here ͑Hz-MHz͒.…”

“…Charge transport at time-scale is reflected in the frequency domain around Ϸ Ϫ1 , which allows us to unravel different dynamical processes. In a recent study 9 it has been demonstrated that the finite transit time t of holes in PPV-based hole-only devices is reflected in the admittance. From the specific frequency-dependent response the hole mobility could be derived.…”

“…9 Changing the applied voltage leads to injection of additional space charge. Under the influence of the bias field, the injected charge moves into the device to relax to the new equilibrium space-charge distribution.…”

“…͑4͒ of Ref. 9. The relaxation time is obtained by maximizing Ϫ⌬B SC ϭ C 0 ϪIm(Y SC ) with respect to , giving Ϸ0.29 ϫ t .…”

Migration-assisted energy transfer at conjugated polymer/metal interfaces

“…In our study, the intermediate dielectric layer of LiF has a similar dielectric constant ͑ ϱ Ϸ 2͒ as the emissive conjugated polymer. 24,25 Therefore, a direct substitution of Eq. ͑2͒ into the diffusion equation can be made, extending the distance x from the polymer/spacer interface with the spacer thickness th.…”