High resolution measurement of localized-state distributions from transient photoconductivity in amorphous and polymeric semiconductors

Abstract

The energy resolution of a method for measuring localized-state distributions in amorphous and polymeric semiconductors has been improved in terms of Tikhonov regularization. The method is based on the analysis of transient photoconductivity data using Laplace transforms, and is valid for both pre- and postmonomolecular recombination regimes of the transient photoconductivity. The improvement of the energy resolution is shown using transient photoconductivity data numerically generated from model localized-state distributions appropriate for the materials. In addition, the measurement of localized-state distributions from time-of-flight transient photocurrents is examined. The applicability of the method with improved energy resolution is demonstrated for undoped hydrogenated amorphous silicon, poly(para-phenylene vinylene) and poly(methylphenylsilane).