An indium tin oxide (ITO) film with low carrier concentration (n), high mobility and high work function (FITO) is a beneficial material for the front electrode in heterojunction silicon (HJ) solar cells due to its low freecarrier absorption in the near-infraredwavelength and lowSchottky barrier height at the ITO/emitter-layer front contact. This lowfree-carrier absorption aswell as the lowSchottky barrier height increase the open-circuit voltage (Voc) and the short-circuit current density (Jsc), which in turn increases the overall cell efficiency (.). Hence, ITO films with lower n, higher mu and higher FITO were prepared by controlling the density of the interstitial oxygen [Oi] in the films and used as anti-reflection electrodes in HJ solar cells. With increasing [Oi] in the ITO, the preferential orientation of the (222) crystalline plane became more dominant. The FITO and increased from 4.87 eV and 38.9 cm(2) V-1 s(-1) to 5.04 eV and 48.79 cm(2) V-1 s(-1), respectively, whereas n decreased from 4.7 x 10(20) cm(-3) to 2.8 x 10(20) cm(-3). We attribute these changes to the chemisorbed oxygen into the ITO films, while the decrease of n is due to the ability of interstitial oxygen to capture electron, and the increase of mu is due to the reduction in free-carrier scattering. These ITO filmswere used to fabricate HJ solar cells. As [Oi] in the ITO film increased, the device performance improved and the best cell performancewas obtained with Voc of 714 mV, Jsc 34.79 mA/cm(2) and. of 17.82%. By computer simulation, we found that the higher FITO and but lower n were responsible for the enhanced cell performance. The cell performance, however, deteriorated due to poor film properties when [Oi] exceeded concentration limit from 3.2 x 10(20) cm(-3). (C) 2013 Elsevier B. V. All rights reserved.