Inverted small molecule organic photovoltaic cells on reflective substrates

We demonstrate top-illuminated, inverted, small molecule photovoltaic cells grown on reflective substrates employing copper phthalocyanine as the donor and 3,4,9,10-perylenetetracarboxylic bis-benzimidazole as the acceptor, with a sputter-deposited transparent indium tin oxide top cathode and a metal anode, thereby reversing the conventional charge extraction properties of these contacts. The best device achieved a peak power conversion efficiency of 0.74 +/- 0.03%, reasonably consistent with the optical simulations under 1 sun AM1.5G illumination giving 0.83 +/- 0.02%. This work suggests that inverted organic solar cells grown on reflective substrates have potential uses such as for power-generating coatings on opaque surfaces. c 2008 American Institute of Physics. [DOI: 10.1063/1.3005173]