Space-charge limited surface currents between two semi-infinite planar electrodes embedded in a uniform dielectric medium

作者：De Visschere P^*; Woestenborghs W; Neyts K

来源：Organic Electronics, 2015, 16: 212-220.

DOI：10.1016/j.orgel.2014.10.036

• Photoconductor
• Interdigitated electrode
• Space-charge limited current
• Photocurrent
• Complex potential
• Conformal transformation

We extend the one-dimensional space-charge limited current theory to a two-dimensional geometry where current flows in a thin layer between two coplanar semi-infinite electrodes. It is shown that the surface charge density in the gap between the electrodes is the finite Hilbert transform of the in-plane component of the electric field. This enables us to derive analytical expressions for the field and charge density for single carrier injection and for photo-carrier extraction by solving a non-linear integral equation for the field. The analytical expressions have been verified by numerical calculations. For the in-plane geometry, the one-dimensional Mott-Gurney equation J = 9/8 mu is an element of V-2/L-3 is replaced by a similar K = 2/pi mu is an element of V-2/L-2 equation. For extraction of photo-generated carriers the one-dimensional J similar to g(3/4)V(1/2) dependence is replaced by a K similar to g(2/3)V(2/3) dependence, where g is the generation rate of photo-carriers. We also extend these results to take into account trapping. We show experimental evidence obtained with an organic photoconductor confirming the predicted voltage, width and generation dependencies.

• 出版日期2015-1