Degradation process in organic thin film devices fabricated using P3HT

The stability of regioregular poly (3-hexylthiophene 2,5-diyl) (P3HT) thin films sandwiched between indium tin oxide (ITO) and aluminium (Al) electrodes have been investigated under normal environmental conditions (25 degrees C and R,H-45-50%). Electrical and optical properties of ITO/P3HT/Al devices have been studied over a period of 30 days. Mobility p of the order of 10(-4) cm(2)/V-s has been obtained from the V-2 law in the as-deposited P3HT films. Scanning electron microscopy (SEM) investigations show blistering of Al contacts in devices with a poly(3,4-ethylenedioxythiophene) (PEDOT) interlayer on application of voltage whereas no blistering is seen in devices without PEDOT. The results have been explained in terms of trap generation and propagation and the moisture-absorbing nature of PEDOT.