Small molecule organic planar and bulk heterojunction photovoltaic cells were fabricated using aluminum phthalocyanine chloride (AlPcCl) or copper phthalocyanine (CuPc) as a donor. While both AlPcCl and CuPc cells have similar short-circuit current, the power conversion efficiency of the AlPcCl cells is about 1.8 times higher than that of the CuPc cells because of the higher open-circuit voltage in the AlPcCl cells. The large open-circuit voltage is due to the large highest occupied molecular Orbital (HOMO) energy of AlPcCl. The maximum power conversion efficiency is 2.0% under I sun standard AM1.5G solar illumination of 100 mW/cm(2). (C) 2009 Elsevier B.V. All rights reserved.