The effect of active layer (amorphous indium–gallium–zinc oxide, a‐IGZO) splitting on the performances of back‐channel‐etched (BCE) and etch‐stopper (ES) thin‐film transistors (TFTs) on polyimide substrate is studied. While the performance of BCE TFT is independent of active layer splitting, the performance of ES TFT is improved significantly by splitting the active layer into 2–4 µm width along the channel. The saturation mobility is enhanced from 24.3 to 76.8 cm2 V−1 s−1 and this improvement is confirmed by the operation of a ring oscillator made of the split TFTs also. X‐ray photoelectron spectroscopy (XPS) analysis of the split a‐IGZO indicates the incorporation of F at the island interface and thus improves the top interface quality, leading to a significant improvement of the top channel TFT mobility from 0.25 to 24.22 cm2 V−1 s−1. This improvement is correlated with bonding of In with F at the top interface according to XPS results. The bias stability, hysteresis, and mechanical stability of the ES a‐IGZO TFT are also remarkably improved by splitting a‐IGZO active layer.

Solution-processed metal-oxide thin-film transistors (TFTs) are considered as one of the most favorable devices for next-generation, large-area flexible electronics. In this paper, we demonstrate the excellent material properties of lanthanum−zinc oxide (LaZnO) thin films deposited by spray pyrolysis and their application to TFTs. The threshold voltage of the LaZnO TFTs shifts toward positive gate voltage, and the mobility decreases with increasing lanthanum ratio in ZnO from 0 to 20%. The purification of the LaZnO precursor (P-LaZnO) further improves the device performance. The P-LaZnO TFT exhibits a field-effect mobility of 22.43 cm 2 V −1 s −1 , zero hysteresis voltage, and negligible threshold voltage V TH shift under positive bias temperature stress. The enhancement in the electrical properties is due to a decrease in grain size, smooth surface roughness, and reduction in the trap density in the LaZnO film. X-ray photoelectron spectroscopy (XPS) results confirm the presence of La in the TFT channel and at/near the interface of the LaZnO and ZrO x gate insulator, leading to fewer interfacial traps. The flexible P-LaZnO TFT fabricated on the polyimide substrate exhibits a mobility of 17.64 cm 2 V −1 s −1 and a negligible V TH shift under bias stress. Also, the inverter made of LZO TFTs is working well with a voltage gain of 17.74 (V/V) at 4 V. Therefore, the LaZnO TFT is a promising device for next-generation flexible displays.

Advancement in thin-film transistor (TFT) technologies has extended to applications that can withstand extreme bending or folding. The changes of the performances of amorphous-indium-gallium-zinc-oxide (a-IGZO) TFTs on polyimide substrate after application of extreme mechanical bending strain are studied. The TFT designs include mesh and strip patterned source/drain metal lines as well as strip patterned a-IGZO semiconductor layer. The robustness of the a-IGZO TFTs with the strain of 2.17% corresponding to the radius of 0.32 mm is tested and no crack generation even after 60 000 bending cycles is found. The split of source/drain electrodes and semiconductor layer can improve the mechanical bending stability of the TFTs. This can be possible by using conventional TFT manufacturing process so that this technology can be easily applied to build robust TFT array for foldable displays.

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