Charge Mobility and Photovoltaic Behavior of MEH-PPV Films Prepared by Various Methods

Charge carrier mobility and photovoltaic parameters was studied in poly[2-methoxy-5-(2´-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) based films prepared by different methods. Polymer films have been obtained by drop casting and new method of slow solvent elimination (SSE). Transient currents demonstrate non-dispersive and dispersive behavior in SSE and drop-cast films, respectively. In SSE films, hole drift mobility increases from 2.2middot10^-6 to 7.0middot10^-6 cm²V^-1s^-1 with the electric field increase from 4.2middot10⁴ to 2.9middot10⁵ Vmiddotcm^-1. These values are greater than the corresponding ones in drop-cast films by a factor of 4-5. This behavior indicates the difference in the morphology of the MEH-PPV films obtained by different methods. Possible reasons of the observed mobility enhancement in the SSE films are discussed