A monolithic fabrication platform for intrinsically stretchable polymer transistors and complementary circuits

TL;DR

This paper presents a universal monolithic photolithography process enabling high-density, high-performance stretchable complementary polymer transistors and circuits, including oscillators and neuron circuits, with significant speed improvements.

Contribution

A novel, scalable fabrication platform for stretchable polymer transistors and circuits that overcomes material-specific limitations and enhances device performance and integration density.

Findings

Achieved record integration density of 55,000 cm^-2 for stretchable OTFTs

Realized stretchable ring oscillators exceeding 1 kHz, a 60-fold increase over previous state

Demonstrated stretchable neuron circuits with modulated output frequency

Abstract

Soft, stretchable organic field-effect transistors (OFETs) can provide powerful on-skin signal conditioning, but current fabrication methods are often material-specific: each new polymer semiconductor (PSC) requires a tailored process. The challenge is even greater for complementary OFET circuits, where two PSCs must be patterned sequentially, which often leads to device degradation. Here, we introduce a universal, monolithic photolithography process that enables high-yield, high-resolution stretchable complementary OFETs and circuits. This approach is enabled by a process-design framework that includes (i) a direct, photopatternable, solvent-resistant, crosslinked dielectric/semiconductor interface, (ii) broadly applicable crosslinked PSC blends that preserve high mobility, and (iii) a patterning strategy that provides simultaneous etch masking and encapsulation. Using this platform, we achieve record integration density for stretchable OTFTs (55,000 cm^-2), channel lengths down to 2 um, and low-voltage operation at 5 V. We demonstrate photopatterning across multiple PSC types and realize complementary circuits, including 3 kHz stretchable ring oscillators, the first to exceed 1 kHz and representing more than a 60-fold increase in stage switching speed over the state of the art. Finally, we demonstrate the first stretchable complementary OTFT neuron circuit, where the output frequency is modulated by the input current to mimic neuronal signal processing. This scalable approach can be readily extended to diverse high-performance stretchable materials, accelerating the development and manufacturing of skin-like electronics.