Estimation of the concentration of deep traps in organic photoconductors using two-photon absorption

TL;DR

This paper introduces a reliable method to estimate deep trap concentrations in organic photoconductors using two-photon absorption, which impacts charge transport analysis in organic electronic devices.

Contribution

A new method based on charge dependence measurements under two-photon excitation for estimating deep trap density in organic materials.

Findings

Method successfully estimates trap density in MEH-PPV

Advantages and limitations of the method are discussed

Experimental results demonstrate the method's applicability

Abstract

Typically, amorphous organic materials contain high density of traps. Traps hinder charge transport and, hence, affect various working parameters of organic electronic devices. In this paper we suggest a simple but reliable method for the estimation of the concentration of deep traps (traps that keep carriers for a time much longer than the typical transport time of the device). The method is based on the measurement of the dependence of the total charge, collected at the electrode, on the total initial charge, uniformly generated in the transport layer under the action of a light pulse. Advantages and limitations of the method are discussed and an experimental example of the estimation of the density of deep traps in photoconductive organic material poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene (MEH-PPV) is provided.