Research of carrier mobility in NPD through negative differential susceptance spectra

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 210023, P.R. China
² College of automation, Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210023, P.R. China

^b e-mail: iamchaotang@gmail.com

Received: 16 July 2014
Revised: 21 October 2014
Accepted: 7 November 2014
Published online: 12 December 2014

Abstract

In this paper, the hole carrier mobility of organic semiconductor N,N′-diphenyl-N,N′bis(1,1′-biphenyl)-4,4′-diamine (NPD) was researched by negative differential susceptance spectra (−ΔB = −w(C − C_geo) ~ f). Under the condition of space charge limited current (SCLC), through solving the drift current equation and Poisson equation and simulating the spectra −ΔB = −w(C − C_geo) ~ f, the relationship between the peak of −ΔB = −w(C − C_geo) ~ f spectra (¹/_ƒp = τ_p) and the transfer time of carrier (τ_dc) could be achieved to be τ_dc = k × τ_p. So the hole-only device of ITO/NPD/Ag was fabricated to determine the capacitance spectra, and through which its −ΔB = −w(C − C_geo) ~ f could be plotted. According to the relationship of τ_dc = k × τ_p, where k was determined to be 0.56, the transfer time and further the carrier mobility could be obtained. The carrier mobility depended on the electric field according to Poole-Frenkel model was further investigated in this report.