Figure 1

Current-voltage characteristics for (a) $\mathrm{Au}/\mathrm{Pc}/\mathrm{ITO}$ with $L=0.85\mu \mathrm{m}$, (b) $\mathrm{Au}/\mathrm{Tc}/\mathrm{Al}$ with $L=0.65\mu \mathrm{m}$, (c) $\mathrm{Au}/\mathrm{Pc}/\mathrm{Al}$ with $L=0.85\mu \mathrm{m}$. The geometry is planar with sandwich configuration of the electrodes. Curve (a) is linear over all the investigated voltage range ($l=1$) and is given in arbitrary units. Curve (b) exhibits the typical SCLC behavior ($\mathrm{\text{Ohmic regime}}\Rightarrow \mathrm{\text{trap-filling}}\mathrm{\text{transition}}\Rightarrow \mathrm{\text{SCLC regime}}$). Curve (c) exhibits a more complicated behavior very likely related to deep traps distributed around two different energy levels.Reuse & Permissions

Figure 2

Relative current noise power spectral density $\mathcal{S}(f)$ for the $\mathrm{Au}/\mathrm{Tc}/\mathrm{Al}$ sample. (a) Ohmic regime: $\mathcal{S}(f)$ does not vary with $V$ in Ohmic condition ($0.3–0.8\mathrm{V}$). (b) Trap-filling regime: $\mathcal{S}(f)$ sharply increases with $V$ during the trap-filling transition ($0.8–2\mathrm{V}$). (c) Space-charge-limited current regime: $\mathcal{S}(f)$ decreases approximately as $1/V$ ($>2\mathrm{V}$). The two-phases medium is shown in the insets. The horizontal arrows represent the current direction. The white areas represent filled traps, i.e., insulating sites characterized by $s_{\mathrm{SCLC}}(f)$ noise. The dark areas represent empty traps, i.e., conductive sites characterized by $s_{\Omega }(f)$ noise. (a) The quasi-Fermi level $E_F\ll E_t$, almost all deep traps are empty. Transport is Ohmic. (b) The quasi-Fermi level is moving through the trap level, $E_F\sim E_t$, filling the traps. Tortuous insulating patterns are generated inside the conductive matrix, leading to nonequilibrium condition at the Ohmic-insulating interface and excess fluctuations. (c) The quasi-Fermi level $E_F\gg E_t$, the traps are mostly filled. The system is characterized by steady-state space-charge-limited current fluctuations decreasing with $V$. Darker areas represent residual conductive sites, shallower tails of Gaussian distributed traps.Reuse & Permissions

Figure 3

Log-log plot of the voltage dependence of the relative fluctuation power spectral density at frequency $f=20\mathrm{Hz}$ for (a) $\mathrm{Au}/\mathrm{Pc}/\mathrm{ITO}$, (b) $\mathrm{Au}/\mathrm{Tc}/\mathrm{Al}$, (c) $\mathrm{Au}/\mathrm{Pc}/\mathrm{Al}$. Data (a) are given in arbitrary units, mostly for reference purpose, and correspond to Ohmic behavior over all the voltage range. The $I\mathrm{\text{−}}V$ characteristics for the same samples are plotted in Fig. 1.Reuse & Permissions