A possible mechanism for the negative capacitance observed in organic devices

TL;DR

This paper investigates the mechanism behind negative capacitance in organic devices, proposing that ion accumulation at interfaces creates surface states leading to observed inductive behavior, supported by simulations.

Contribution

It introduces a kinetic model explaining negative capacitance in organic devices through ion-driven surface state formation and validates it with simulations.

Findings

Negative capacitance arises from ion accumulation at interfaces.

Surface states enhance junction current, causing inductive effects.

Simulations match impedance, capacitance, and current response measurements.

Abstract

The mechanism of negative capacitance, e.g. inductance, induced by a sufficient electrical field in the organic device is investigated. The cations in organic bulk are proposed to be driven by the applied voltage and to accumulate at the interface, and further to generate the surface states or media states. These states result in a larger junction current through the device, indicating the negative capacitances which are simulated in three situations: impedance spectrum, capacitance measurement and current response. This simple kinetic model may be helpful to understand why the negative capacitance phenomenon is observed in various organic devices.