Highly transparent Nb-doped indium oxide electrodes for organic solar cells

Abstract

The authors investigated the characteristics of Nb-doped In2O3 (INbO) films prepared by co-sputtering of Nb2O5 and In2O3 for use in transparent anodes for organic solar cells (OSCs). To optimize the Nb dopant composition in the In2O3 matrix, the effect of the Nb doping power on the resistivity and transparency of the INbO films were examined. The electronic structure and microstructure of the INbO films were also investigated using synchrotron x-ray absorption spectroscopy and x-ray diffraction examinations in detail. At the optimized Nb co-sputtering power of 30W, the INbO film exhibited a sheet resistance of 15 Omega/sq, and an optical transmittance of 86.04% at 550 nm, which are highly acceptable for the use as transparent electrodes in the fabrication of OSCs. More importantly, the comparable power conversion efficiency (3.34%) of the OSC with an INbO anode with that (3.31%) of an OSC with a commercial ITO anode indicates that INbO films are promising as a transparent electrode for high performance OSCs. (C) 2014 American Vacuum Society.