Reduction of Series Resistance in Organic Photovoltaic Using Low Sheet Resistance of ITO Electrode

The series resistance of organic photovoltaic (OPV) devices was decreased by reducing the sheet resistance (R(sh)) of the indium tin oxide (ITO) electrode, which leads to increasing device efficiency. The performance of bulk heterojunction OPVs was critically dependent on R(sh) of the ITO electrode. Upon reducing R(sh) of the ITO from 39 to 8.5 Omega/square, the fill factor and power conversion efficiency of OPV was improved (from 0.407 to 0.580 and from 1.63 +/- 0.2 to 2.5 +/- 0.1%, respectively) under an AM1.5 simulated solar intensity of 100 mW/cm(2). The dependence of the series resistance on R(sh) of the ITO suggests the dominance of the bulk resistance of the ITO electrode as a limiting factor in practical cell efficiencies. (C) 2008 The Electrochemical Society. [DOI: 10.1149/1.3055339] All rights reserved.