A stable small-molecule organic photovoltaic device with structure of ITO\donor\acceptor\buffer\cathode is presented. A thin layer (similar to 60 angstrom) of tris-8-hydroxy-quinolinato aluminum (Alq(3)) instead of bathocuproine (BCP) is adopted as the buffer of the device, resulting in 150 times longer lifetime. The power conversion efficiency of the device is 2.11% under 75 MW/cm(2) AM1.5G simulated illumination, and no perceptible efficiency degradation is observed for long-term storage of the device in vacuum or nitrogen-filled glove box. More effective blocking of Alq(3) than BCP against diffusion of cathode atoms and permeation of oxygen and/or water molecules is considered as the main reason for the improved performance of the new device. (c) 2005 Elsevier B.V. All rights reserved.