Rapid cleanroom-free fabrication of thread based transistors using three-dimensional stencil-based patterning

Abstract

Applications such as wearable electronics and flexible displays have led to considerable advancement in flexible electronic materials. Textile threads have recently emerged as a flexible substrate with unique properties like biocompatibility, three-dimensional (3D) interfacing, and processability. However, fabrication of transistors and integrated circuits on threads remains a challenge. We address this need with a low-cost, high-throughput and cleanroom-free fabrication method for ionogel-gated organic thread-based transistors. It makes use of a 3D flexible ‘stencil’ to fabricate the active channel area gap. Similar to stencils used in screen printing on two-dimensional substrates, the stencil provides a 3D mask for spatially targeted printing on thread-based substrates. Carbon ink is coated using this 3D stencil on the thread to act as source and drain electrodes, along with poly(3-hexylthiophene), a proven organic semiconductor as a proof of concept. We achieve consistent simultaneous batch fabrication of over tens of transistors with a threshold voltage of − (1.48 ± 0.11) V, an operating region of 0 to −3 V, and an ON/OFF ratio of the order of 102.