We report a room-temperature and high-mobility InGaZnO thin-film transistor on flexible substrate. To gain both high gate capacitance and low leakage current, we adopt stacked dielectric of Y2O3/TiO2/Y2O3. This flexible IGZO TFT shows a low threshold voltage of 0.45 V, a small sub-threshold swing of 0.16 V/decade and very high field-effect mobility of 40 cm(2)/V. Such good performance is mainly contributed by improved gate stack structure and thickness modulation of IGZO channel that reduce the interface trap density without apparent mobility degradation. (C) 2013 Elsevier B.V. All rights reserved.