Non-linear I-V characteristics of MEH-PPV patterned on sub-micrometer electrodes

A sub-micrometer-wide line of a conjugated polymer MEH-PPV [poly(2-methoxy-5-(2-ethyl hexyloxy)-p-phenylene vinylene)] was patterned using a scanning electron microscope (SEM). The spin-coated thin MEH-PPV film was exposed to the electron beam in SEM, resulting in an increase in cross-linking, which reduced the solubility of the MEH-PPV film. The polymer was developed in p-xylene to dissolve the non-irradiated part of the polymer. The width, length and thickness of the active patterned area, determined by the atomic force microscopy (AFM) image, was 500, 200 and 20 nm, respectively. The two-probe current-voltage characteristics of the patterned MEH-PPV line were measured as a function of temperature. The higher field data of the non-linear I-V curves were fitted using the single carrier device model which considered the field and temperature dependent mobility with space charge limited conduction (SCLC). The estimated zero-field hole mobility was of the order of 10^-3 cm²/Vs with an activation energy of 0.038 eV. © 2001 Elsevier Science B.V. All rights reserved.