Low Resistance and High Transparent Amorphous IZTO Electrode Cosputtered by Linear Facing Target Sputtering for Organic Photovoltaics

We report on the characteristics of an amorphous indium zinc tin oxide (a-IZTO) multicomponent electrode cosputtered by linear facing target sputtering (LFTS) using indium tin oxide (ITO) and indium zinc oxide targets for bulk heterojunction organic solar cells (OSCs). Without substrate heating or postannealing, the a-IZTO electrode exhibited a low sheet resistance of 17.48 /square, a high average optical transmittance of 88.1% at a wavelength of 500 nm, and a high work function of 5.22 eV. In addition, the a-IZTO electrode with a root-mean-square (rms) roughness of 0.35 nm shows a much smoother surface than the crystalline ITO electrode (rms roughness of 1.25 nm), due to the absence of bombardment of energetic particles on the IZTO electrode during the cosputtering process. Moreover, the OSC with the a-IZTO anode showed a comparable open-circuit voltage (0.56 V), short-circuit current (9.16 mA/cm(2)), fill factor (68.1%), and power conversion efficiency (3.50%) to an OSC with a commercial crystalline ITO electrode. This indicates that the LFTS-grown a-IZTO electrode is a visible alternative to crystalline ITO electrodes for low cost OSCs, eliminating the need for the annealing or substrate heating step generally required for preparing high quality anode electrodes.