Effects of rapid thermal annealing on electrical, optical, and structural properties of Ni-doped In2O3 anodes for bulk heterojunction organic solar cells

Abstract

The authors investigated the effects of rapid thermal annealing (RTA) on the electrical, optical, and structural properties, and work functions of Ni-doped In2O3 (INO) anodes prepared by a DC/RF co-sputtering process for use in bulk heterojunction organic solar cells (OSCs). By RTA processing at 600 °C, the authors obtained the optimized INO anodes with a sheet resistance of 28 Ω/sq, an optical transmittance of 82.93%, and a work function of 5.02 eV, which are acceptable in OSC fabrication. In particular, the 600 °C annealed INO anode showed much higher optical transmittance in the near infrared wavelength region than the conventional ITO film, even though it had a low resistivity of 5.66 × 10−4 Ω cm. The OSC fabricated on the annealed INO anode showed a higher power convention efficiency of 2.65% than the OSC with as-deposited INO anodes (2.19%) because the fill factors of the OSC are critically dependent on the sheet resistance of the anode.