Flexible In–Ga–Zn–O Thin-Film Transistors on Elastomeric Substrate Bent to 2.3% Strain

In this letter, a photolithographic fabrication process is used to manufacture indium-gallium-zinc-oxide thin-film transistors (TFTs) with mobilities > 10 cm²/Vs directly on a 80 μm thick polydimethylsiloxane (PDMS) substrate. Once the fabrication is completed, the PDMS is detached from a silicon wafer used as carrier substrate. Due to the thermal mismatch between silicon and PDMS, the release results in a reduction of the PDMS area by 7.2%, which leads to the formation of out-of-plane wrinkles on the TFT surface. The reflattening of the wrinkles under tensile strain enables device functionality, while the TFTs are bent up to 2.3% strain. Mechanical stability of the TFTs with our wrinkled approach is shown by electrically characterizing them at bending radii down to 6 mm.