Large area ITO-free organic solar cells on steel substrate

Large area ITO-free organic solar cells on steel substrates are demonstrated. The stainless steel was used as a substrate with excellent barrier properties and as a bottom electrode with very low sheet resistance. The low sheet resistance of the steel electrode allows manufacturing of large area devices with good performance. The individual cells with the size of 5 x 10 cm(2) and efficiency of 1.3% were manufactured. The OPV cells with steel electrode demonstrate fill factor in the range of 58-69%, as measured under illumination through a mask with an aperture of 1.0 x 1.0 cm(2). A thermally evaporated semitransparent top cathode, contained ZnS and thin metal layers, was used to complete the device stack. In order to quantitate effect of the cathode transmittance, the optical simulations using the transfer-matrix formalism has been performed. (C) 2012 Elsevier B.V. All rights reserved.