Oxygen- and water-based degradation in [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) films

Abstract

Effects of in situ oxygen/water exposure on the energetics of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) films are presented. For oxygen exposure, the work function is downshifted by ≈0.15 eV compared to the ideal integer charge transfer (ICT) curve for pristine PCBM, which is incompatible with significant introduction of electron trap states or p-doping. Water induces the highest occupied molecular orbital (HOMO) structure to undergo strong, irreversible modifications accompanied by a chemical interaction with PCBM. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.