Study of carrier dynamics of N,N′-diphenyl-N,N′bis (1,1′-biphenyl)-4,4′-diamine (NPB) through the frequency dependence of impedance spectroscopy and particle swarm optimization algorithm

¹ Key Laboratory for Organic Electronics and Information Displays (KLOEID), Singapore-Jiangsu Joint Research Center for Organic/Bio Electronics & Information Displays (COEID), Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210046, P.R. China
² College of automation, Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210046, P.R. China

^a e-mail: iamchaotang@gmail.com

Received: 16 December 2013
Revised: 13 March 2014
Accepted: 20 March 2014
Published online: 24 April 2014

Abstract

In this paper, carrier dynamics in N,N′-diphenyl-N,N′bis(1,1′-biphenyl)-4,4′-diamine (NPB) was studied using impedance spectroscopy (IS) and particle swarm optimization algorithm (PSO). We applied PSO to fit the frequency dependence of impedance spectroscopy of NPB, and achieved the charge-carrier transit time and the dispersive parameters of NPB, and then obtained carrier mobility. The impacts of the dispersive degree on the impedance had been analyzed. Though PSO, the three unknown parameters, charge-carrier transit time τ_dc and dispersive degree M, α in the admittance model were achieved simultaneously. The results verified the reliability of this method. Furthermore, we have presented the advantages of PSO compared with the traditional nonlinear least squares algorithm. In our limited knowledge, this paper begins the work to study materials in the deep level of algorithm