LAUSR

DOI: 10.1002/aelm.201800707 layers have also been demonstrated with impressive characteristics in next-generation electronics,[9–11] biological/chemical sensors,[15–17] and photoelectrical detectors,[18,19] etc. Even though the In2O3 material may not be the best material choice for the future sustainability because of the scarcity of In, it still attracts a great deal of attention due to its excellent electrical properties.[20–22] For instance, Kim et al. demonstrated a solution-processed metaloxide thin film transistors (e.g., In2O3, IZO, ZnO) via combustion process at a temperature as low as ≈200 °C, which yielded a high mobility of 13 cm2 V−1 s−1.[20] Meng et al. fabricated a electrospun fiberto-film processed metal-oxide thin film transistors (i.e., In2O3, IZO, IZrZO) with Al2O3 dielectrics, where these devices displayed an impressive on/off current ratio of 107 and a field effect mobility of 25 cm2 V−1 s−1.[21] The physical properties of In2O3 NFs could also be enhanced via crosslinking welding process developed by Cui et al.[22] However, until now, most of the 1D In2O3-based devices are generally operated in the n-type depletion-mode (D-mode), particularly featured with a negative threshold voltage (VTH), a high off-state current, and a low ratio of on-state/off-state current (Ion/Ioff). This inadequate device performance can be predominantly attributed to the excess carriers existed in the In2O3 NFs or nanowires (NWs), which are typically originated from the oxygen vacancies acting as the donor-like defects. Notably, the large negative VTH means that there is a non-zero channel current yielded at a zero gate Although In2O3 nanofibers (NFs) are considered as one of the fundamental building blocks for future electronics, the further development of these NFs devices is still seriously hindered by the large leakage current, low on/off current ratio (Ion/Ioff ), and large negative threshold voltage (VTH) due to the excess carriers existed in the NFs. A simple one-step electrospinning process is employed here to effectively control the carrier concentration of In2O3 NFs by selectively doping strontium (Sr) element to improve their electrical device performance. The optimal devices (3.6 mol% Sr doping concentration) can yield the high field-effect mobility (μfe ≈ 3.67 cm2 V−1 s−1), superior Ion/Ioff ratio (≈108), and operation in the energy-efficient enhancement-mode. High-κ Al2O3 thin films can also be employed as the gate dielectric to give the gate voltage greatly reduced by 10× (from 40 to 4 V) and the μfe substantially increased by 4.8× (to 17.2 cm2 V−1 s−1). The electrospun E-mode Sr-In2O3 NF field-effect transistors (NFFETs) can as well be integrated into full swing of inverters with excellent performances, further elucidating the significant advance of this electrospinning technique toward practical applications for future low-cost, energy-efficient, large-scale, and high-performance electronics.