Charge injection mechanism across the Au-poly(3-hexylthiophene-2,5-diyl) interface

The nature of charge injection has been investigated across the Au-poly(3-hexylthiophene-2,5-diyl) (P3HT) interface of two kinds: P3HT on Au (bottom contact) and Au on P3HT (top contact). The J-V characteristics of a Au(bottom)/P3HT/Au(top) sandwich cell are analyzed by using the Fowler-Nordheim model and the hole barrier height at the top and bottom contacts has been estimated. The top contact showed a higher barrier height in comparison to the bottom contact. The quenching of photoluminescence spectra and the disappearance of characteristic P3HT peaks from the absorption spectra for the top contact supports that the ionically sputtered gold atoms on the polymer give rise to greater density of interfacial trap sites than those at bottom interface. (c) 2007 American Institute of Physics.