Reusable printed zirconium oxide on CNT-paper for high performance thin-film transistors

Metal oxides represent a highly attractive class of materials for the development of sustainable electronic devices, which demands novel strategies that enable component reusability and reduced environmental impact, while maintaining high performance. In the present work, we report the fabrication of printed thin-film transistors (TFTs) based on eco-friendly and solution-processable metal oxides. The device is composed of two independently fabricated parts, one is a spray-coated zinc oxide (ZnO) active layer deposited on patterned ITO/glass electrodes, and the other a reusable gate dielectric/electrode structure comprising screen-printed zirconium oxide (ZrO2) on a carbon nanotubes paper substrate (CNT-paper), with the ZrO2 nanopowder synthesized by microwave-assisted hydrothermal route. These two components are placed in mechanical contact by pressure allowing effective physical contact between the layers while enabling the ZrO2/CNT-paper structure to be detached and reused, as demonstrated across the twelve samples investigated in this study. The obtained TFTs exhibit excellent electrical performance, with an Ion/Ioff > 104, onset voltage as low as Von ≈ 0.79 ± 0.08 V, and subthreshold swing of SS = 119.5 ± 18.7 mV dec−1. Furthermore, the transistors showed excellent stability under cyclic testing, such as multiple sequential double-sweep transfer curves and cycles of dynamic gate-pulsed response measurement. Notably, after detachment and reapplication of the ZrO2/CNT-paper structure onto a new Glass/ITO/ZnO device, the transistor characteristics are preserved, leading to low error and transfer profiles with no visible degradation occurring. Our findings on gate reusability pave the way for more sustainable and modular transistor applications.