The effects of trap density on current bistability and negative differential resistance in organic bistable devices

Current bistable properties and negative differential resistance (NDR) behaviors of organic bistable devices (OBDs) with a single layer were simulated by using Shockley-Reed statistics for the trap population. The current-voltage (I-V) curves were calculated to investigate the effects of the trap density on the NDR characteristics of current bistabilities in the OBDs. The simulation results of the I-V curves showed that the current bistability and the NDR behavior of the OBDs were dominantly attributed to the trapped electrons in the organic layer. The NDR behavior of the I-V curve appeared with increasing trap density, and the increasing rate of the internal electric field caused by the trapped electrons became larger than that of the external electric field due to the applied voltage. This resulted in the appearance of NDR behavior in the I-V curves. These results can help improve understanding of the effects of the trap density on the current bistability and the origin of the NDR behavior in the I-V characteristic in OBDs.