Comparative study of high-k Metal Oxide-PVP/PMMA hybrid Gate Dielectrics for low-temperature, all-solution-processed flexible In 2 O 3 thin film transistors

Abstract

Flexible thin-film transistors (TFTs) require dielectric layers that simultaneously provide high capacitance, low leakage current, and mechanical robustness at processing while being compatible with low-temperature processing on polymer substrates. Here, we report a systematic comparative study of organic-inorganic hybrid gate dielectrics obtained by blending a PVP/PMMA co-polymer with five high-k metal oxides (Al2O3, HfO2, ZrO2, Gd2O3 and Y2O3) via a low temperature sol-gel route and spin-coating, followed by ≤200°C thermal treatment. The dielectric properties were evaluated in rigid and flexible MIM capacitors and subsequently integrated into fully solutionprocessed In₂O₃ TFTs fabricated on glass and flexible PEN substrates. Among the systems, ZrOx-PVP/PMMA delivers the highest dielectric constant which, in rigid TFTs, enables a saturation mobility of 1.22 cm^2/Vs, an I_ON /I_OFF ratio of 10e6 , threshold voltage of 1 V and a subthreshold swing of 0.75 V/dec, while AlOx-PVP/PMMA shows increased hysteresis consistent with residual -OH related traps. On flexible PEN, devices using HfOx-PVP/PMMA and ZrOx-PVP/PMMA retain stable operation under bending radii down to 7.5 mm with negligible parameter variation, highlighting the mechanical resilience of the hybrid networks. This systematic comparison of five metal-oxide chemistries within the same PVP/PMMA matrix demonstrates the viability of low-temperature, all-solution processed of hybrid dielectrics for next-generation flexible oxide electronics.