利用通用迁移率模型计算有机二极管的交流阻抗谱

Alternating-current Impedance Spectroscopy of Organic Diodes Based on Unified Mobility Model

摘要:

推导出了有机二极管交流阻抗谱的公式，当迁移率为常数时的计算结果与文献中的解析公式相符合，表明推出的公式和编写的程序是正确的。进一步根据文献中与温度、载流子浓度和电场强度有关的通用迁移率模型，计算了NRS PPV有机二极管的交流阻抗谱。结果表明阻抗的实部总是取正值，虚部总是取负值。阻抗的实部和虚部的绝对值在低频极限下的数值都是随温度和直流偏压增大而减小。实部总是频率的单调减函数，且减小的速率随温度和直流偏压增大而变慢；虚部绝对值在低温下是频率的单调减函数，在高温下将出现极大值，极值的峰高随温度和直流偏压增大而减小，极值位置相应地出现蓝移。

Abstract:

The formula for AC impedance spectroscopy (IS) of organic semiconducting diodes was derived. The agreement of numerical results as mobility being constant with analytic formula in literature verifies the correctness of our formula and program. The program is then used to calculate IS of organic NRS PPV diode based on the mobility model as a function of temperature, electric field and charge carrier concentration. The results show that the real and imaginary parts of IS for NRS PPV diode always take positive and negative values, respectively, and their absolute values at low frequency always decrease as temperature and bias increase. The real part always is an increasing function of frequency, and the slope decreases as the increase of temperature and bias. The imaginary part is a decreasing function of frequency at low temperature, and a peak appears at high temperature. The peak values decrease and the locations of peak shift blue as temperature and bias increasing.