Determining charge carrier mobility in Schottky contacted single-carrier organic devices by impedance spectroscopy

¹ College of Optical and Electronic Technology, China Jiliang University - Hangzhou 310018, China
² School of Physical Science and Technology, Lanzhou University - Lanzhou 730000, China

^(a) Present address: College of Optical and Electronic Technology, China Jiliang University - Hangzhou 310018, China; tangy@cjlu.edu.cn
^(b) yqpeng@lzu.edu.cn (corresponding author)

Received: 30 July 2015
Accepted: 26 September 2015

Abstract

Impedance spectroscopy (IS) is one of the most important methods for analyzing transport properties of semiconducting thin films. At present carrier mobility can be determined by IS methods only for Ohmic contacted single-carrier devices, which hinders the use of the IS method for determining the carrier mobility of thin films with high-lying lowest unoccupied molecular orbits or low-lying highest occupied molecular orbits. Based on the theory of space charge limited current conduction and thermionic emission at metal-organic interface, we developed a numerical IS model for single-carrier organic devices with Schottky injection contact. With the help of this model, a concise empirical formula is obtained from which the carrier mobility can be determined from the characteristic frequency of the negative differential susceptance and the Schottky energy barrier height at the injection contact.