Study of charge-carrier relaxation in a disordered organic semiconductor by simulating impedance spectroscopy

M. Mesta, J. Cottaar, R. Coehoorn, P.A. Bobbert

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Abstract

Impedance spectroscopy is a very sensitive probe of nonstationary charge transport governed by charge-carrier relaxation in devices of disordered organic semiconductors. We simulate impedance spectroscopy measurements of hole-only devices of a polyfluorene-based disordered organic semiconductor by solving a time-dependent three-dimensional master equation for the occupational probabilities of transport sites in the semiconductor. We focus on the capacitance-voltage characteristics at different frequencies. In order to obtain good agreement with the measured characteristics, we have to assume a lower strength of a Gaussian energy disorder than obtained from best fits to the stationary current density-voltage characteristics. This lower disorder strength is in agreement with dark-injection studies of nonstationary charge transport on the same devices. The results add to solving the puzzle of reconciling nonstationary with stationary charge-transport studies of disordered organic semiconductors.
Original languageEnglish
Article number213301
Pages (from-to)1-4
JournalApplied Physics Letters
Volume104
DOIs
Publication statusPublished - 2014

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