Room temperature strategy for high-performance Pr:IZO/Al2O3 thin-film transistors: Enhanced stability of light-induced bias stress and applications in flexible devices

Abstract

This study focuses on the development of high-performance Pr:IZO/Al₂O₃ bilayer metal-oxide thin-film transistors (MOTFTs) prepared at room temperature, addressing critical challenges in achieving high mobility, stability, and adaptability for flexible electronics. By optimizing process parameters and layer thicknesses, the optimal configuration of Pr:IZO (14.0 nm) and Al₂O₃ (3.1 nm) was identified. TFTs fabricated on glass substrates demonstrated exceptional performance, including a mobility of 26.1 cm²/V·s, a subthreshold swing (SS) of 0.22 V/dec, an on/off ratio of 4.2 × 10⁸, and outstanding stability under negative bias illumination stress (NBIS), with a threshold voltage shift of only -4.5 V after 3600 s. On flexible PI substrates, Pr:IZO/Al₂O₃-TFTs achieved even higher mobility (29.8 cm²/V·s) and excellent NBIS stability with a threshold voltage shift of only -4.3 V after 3600 s, highlighting their application potential in flexible electronics. Depth-etched XPS analysis revealed that Pr doping reduced the weakly bonded oxygen content while increasing lattice oxygen, improving carrier transport efficiency. Additionally, the Al₂O₃ capping layer suppresses interfacial oxygen vacancies, stabilizes lattice oxygen, and induces negative charge field-effect passivation at the oxygen-rich interface, reducing trap states and further improving device stability.