Near-Field Spectroscopic Studies of Fluorescence Quenching by Charge Carriers

Abstract

Near-field scanning optical microscopy (NSOM) with an electrically biased probe is a technique that allows the imaging of charge carrier drift (mobility), carrier concentration, and their interaction with excitations (excitons) in functioning devices. This technique has been applied to poly[2-methoxy, 5-(2'-ethyl-hexyloxy)-p-phenylenevinylene](MEH-PPV) and tetracene-doped pentacene devices. Space and time resolved data show that quenching by charge carriers and charge trapping by defect sites in the organic materials, specifically in the presence of oxygen, is found to be of critical importance in the understanding and further development of more efficient and durable devices.