Due to the advantages of being light, conformable, nonfragile, and bendable, flexible electronic devices have been considered for various applications such as flexible displays, bendable memories, e-textiles, radio frequency identifications (RFIDs), artificial skin/muscles, and wearable electronics. [1,2] Compared to rigid devices, the main challenges of flexible devices are finding suitable materials and fabrication methods to overcome the inherent barrier of low glass-transition temperature (T g ) for flexible substrates.Organic small molecules and polymers are flexible, but the corresponding devices are subject to issues resulting from short lifetime and difficult packaging. Conventional hydrogenated amorphoussilicon (a-Si:H) thin-film transistors (TFTs) can be prepared on flexible plastic substrates due to the low processing temperature of plasma-enhanced chemical vapor deposition (PECVD) (<200 C). [3] However, reduced carrier mobility and unstable characteristics under gate-bias stress limit their applications in flexible electronics. [4] Although low-temperature polysilicon (LTPS) TFTs show high mobility and stable characteristics, they are still unsuitable for flexible devices due to the crystallization temperature of polysilicon being higher than the T g of plastic substrates. [5,6] In addition, nanocrystalline-silicon (nc-Si) TFTs can show both good device stability and high carrier mobility (>10 2 cm 2 V À1 s À1 ). However, their high cost is a huge obstacle for industrial production, and the growth rate of nc-Si still requires further enhancement.Transparent oxide semiconductors (TOSs) have attracted considerable research interest because of their superior controllability in carrier generation and excellent optical transparency in the whole visible region. TFTs based on TOSs, such as InGaZnO, GaSnZnO, and AlSnZnInO, have been intensively studied due to the lower processing temperature than nc-Si TFTs, better uniformity than LTPS TFTs, and higher mobility and better stability than a-Si:H TFTs. [7][8][9] Among the state-of-the-art semiconductor materials, amorphous InGaZnO (a-IGZO), which was first fabricated by Nomura et al. in 2003, [10] is one of the most promising options, with an a-IGZO TFT successfully prepared on a flexible polyethylene terephthalate (PET)