Zero Waste and Biodegradable Zinc Oxide Thin-Film Transistors for UV Sensors and Logic Circuits

Bioderived and biodegradable electronics have the capability to reduce significantly waste electrical and electronics equipment (WEEE) and can also be applied to other sectors, where degradation to benign by-products is essential, such as marine, farming, or health monitoring. Herein, the authors report biodegradable thin-film transistors (TFTs) arrays based on zinc oxide (ZnO) active layer using molybdenum (Mo) source, drain, and gate electrodes. The developed TFTs were fabricated at room temperature onto a planarized biodegradable substrate surface and achieved an
${I}_{\text {on}}/{I}_{\text {off}}$
ratio of
$\sim 4\times 10^{{6}}$
, a threshold voltage of
$\sim $
2.3 V, a field-effect mobility in the saturation region of 1.3 cm
$^{{2}}\cdot \text{V}^{-{1}}\cdot \text{s}^{-{1}}$
, and a subthreshold swing of 0.3
$\text{V}\cdot $
dec
$^{-{1}}$
and show stable device performance under stability tests. Based upon the successful fabrication of the ZnO TFT array, the demonstration of a UV sensor (phototransistors mode) and simple logic circuits (inverter and both NAND and NOR gate circuits) are presented. Furthermore, a method to “control” the transience was implemented by using a printed heater that could accelerate the decomposition of material, which opens potential avenue for material recovery and zero waste products.