An efficient single layer organic solar cell based on plain buckminsterfulerence (C-60) has been fabricated. By inserting a very thin N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)benzidine layer between the indium tin oxide and single C-60 active layer, a short-circuit current of 1.98 mA/cm(2) and an open-circuit voltage of 0.52 V are obtained under 100 mW/cm(2) AM1.5G simulated illumination. The highest power conversion efficiency of 0.414% based on plain C-60 is thus demonstrated, which is the first step to realize an environment-friendly energy source. (C) 2010 Elsevier B.V. All rights reserved.