We present a nonlinear impedance spectroscopy technique and demonstrate its ability to directly measure nonlinear processes including electron-hole recombination and space charge effects in organic-semiconductor-based diodes and MIS capacitors. The method is based on Fourier analysis of the measured higher harmonic current response to an AC voltage signal. Characterization of the higher harmonic response allows nonlinear impedance spectroscopy to measure material and device properties over a wide range of frequencies, which would otherwise be impossible using conventional impedance spectroscopy. As the higher harmonic signals are purely a product of nonlinear processes, they are independent of the linear device capacitance and resistance. This allows space charge and recombination effects to be investigated at several orders of magnitude higher frequency without fitting to an equivalent circuit model.

我们提出了一种非线性阻抗谱技术，并证明了它能够直接测量非线性过程，包括基于有机半导体的二极管和MIS电容器中的电子-空穴复合和空间电荷效应。该方法基于对交流电压信号测得的更高谐波电流响应的傅立叶分析。高次谐波响应的特性使非线性阻抗谱能够在很宽的频率范围内测量材料和器件的性能，否则，使用常规的阻抗谱是不可能的。由于高次谐波信号纯粹是非线性过程的产物，因此它们与线性器件的电容和电阻无关。