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

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.