Thin-Film Electronics on a Green and Flexible Cellulose-Based Film

Flexible electronics, mostly realized on plastic substrates, enables various technologies to encompass a wider range of innovative applications such as wearables, implantable devices, and flexible sensors. However, this rapidly evolving field equates to a high turnover leading to a substantial electronic waste generation. To address this stark sustainability problem, research has shifted toward greener materials and methodologies for device fabrication. Here, we report the realization of thin-film electronics on triacetyl cellulose (TAC) film derived from a structural compound in plants called cellulose. Resistive temperature sensors based on sputtered Cu are achieved, demonstrating a linear relationship between resistance and temperatures up to 100° C. Multilayered thin-film transistors (TFTs) based on InGaZnO (IGZO) are also realized with an ON-OFF current ratio ≈ 105, effective mobility of 13.2 cm2· V-1·s-1, threshold voltage of -0.2 V, and subthreshold swing of 161 mV·dec-1, which are characteristics comparable to devices fabricated on conventional plastic substrates. At the same time, we fabricated common-source amplifiers with a low-frequency voltage gain of 4.5 dB and a cutoff frequency of 50 Hz in flat condition. These parameters minimally vary (5.6 dB and 40 Hz) when the circuit is mechanically deformed by bending to a radius of 8 mm. Furthermore, the TAC film exhibits dissolvability in organic solvents such as acetone and acids such as acetic acid, nitric acid, and phosphoric acid. These findings demonstrate the potential of a cellulose-based film as an alternative to plastic substrates and its merits for the realization of green electronics.