The applications of thin-film transistors (TFTs) based on oxide semiconductors are limited due to instability under negative bias illumination stress (NBIS). Here, we report TFTs based on solution-processed In₂O₃ semiconductors doped with Pr⁴⁺ or Tb⁴⁺, which can effectively improve the NBIS stability. The differences between the Pr⁴⁺-doped In₂O₃ (Pr:In₂O₃) and Tb⁴⁺-doped In₂O₃ (Tb:In₂O₃) are investigated in detail. The undoped In₂O₃ TFTs with different annealing temperatures exhibit poor NBIS stability with serious turn-on voltage shift (ΔV_on). After doping with Pr⁴⁺/Tb⁴⁺, the TFTs show greatly improved NBIS stability. As the annealing temperature increases, the Pr:In₂O₃ TFTs have poorer NBIS stability (ΔV_on are −3.2, −4.8, and −4.8 V for annealing temperature of 300, 350, and 400 °C, respectively), while the Tb:In₂O₃ TFTs have better NBIS stability (ΔV_on are −3.6, −3.6, and −1.2 V for annealing temperature of 300, 350, and 400 ℃, respectively). Further studies reveal that the improvement of the NBIS stability of the Pr⁴⁺/Tb⁴⁺:In₂O₃ TFTs is attributed to the absorption of the illuminated light by the Pr/Tb4fⁿ—O2p⁶ to Pr/Tb 4fⁿ⁺¹—O2p⁵ charge transfer (CT) transition and downconversion of the light to nonradiative transition with a relatively short relaxation time compared to the ionization process of the oxygen vacancies. The higher NBIS stability of Tb:In₂O₃ TFTs compared to Pr:In₂O₃ TFTs is ascribed to the smaller ion radius of Tb⁴⁺ and the lower energy level of Tb 4f⁷ with a isotropic half-full configuration compared to that of Pr 4f¹, which would make it easier for the Tb⁴⁺ to absorb the visible light than the Pr⁴⁺.

Indium zinc tin oxide (IZTO) has emerged as a promising alternative for thin-film transistor (TFT) channels, owing to its high electron mobility, yet it suffers from oxygen vacancies (V _O )-induced negative bias illumination stress (NBIS) instability and slow photocarrier recovery. In this work, we propose titanium (Ti)-doped IZTO (IZTTO) to simultaneously improve bias stability and UV photoresponse. Ti-doped devices exhibit significantly suppressed threshold voltage shifts under NBIS, attributed to V _O passivation and Ti ⁴⁺ -induced sub-bandgap states that capture photogenerated electrons. Moreover, IZTTO TFTs show enhanced UV photoresponse with a high photo-to-dark current ratio (PDCR) and steep pulse edges, especially at 10% Ti doping. Controlled Ti doping thus enables simultaneous improvement in bias stability and UV sensitivity, offering a viable material strategy for high-performance oxide TFTs in displays and UV detection.