Alkyl amine stabilized gold nanoparticles (Au-NPs), with diameters of 1-10 nm, deposited at the interface of the hole-collecting buffer layer [poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)] and poly(3-hexylthiophene):[6,6]-phenyl C(61)-butyric acid methyl ester (P3HT):(PCBM) active layer were found to significantly reduce solar cell performance. The reduced performance was attributed to interactions between the amine based organic stabilizers and the PEDOT:PSS buffer layer. This was confirmed by screening various organic stabilizing ligands at the interfacial layer and measuring the resulting solar cell performances. In addition, it was found that alkyl thiol capped Au-NPs (5-10 nm) incorporated at the buffer layer and their corresponding alkyl thiol stabilized ligands had a lesser impact on the overall performance of the polymer solar cells. (C) 2011 Elsevier B.V. All rights reserved.