Electric Field inside a Hole-Only Device and Insights into Space-Charge-Limited Current Measurement for Organic Semiconductors

It is known that the electric field is nonuniform inside organic electronic devices. However, the physics a few nanometers near interfaces and factors that influence the electric field distribution are still not fully understood. Moreover, the mobility might be nonuniform inside the device, since it is electric-field dependent. However, this has been overlooked in the apprehension of the space-charge-limited (SCL) current in the commonly used Mott–Gurney equation. Here, we carry out 3D multiparticle Monte Carlo simulations to study the electric field and energy diagram in a hole-only device under bias. Coulomb potential is obtained from the solution of the 1D Poisson equation of our system. The influences of the injection barrier, the energetic disorder and the applied bias are studied in detail. The SCL current is compared with that from the Mott−Gurney equation. It is found that the apparent charge mobilities are close to those calculated using the transit time corresponding to the cross point of asympt...

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