Boiling water tolerant organic field-effect transistors enabled by a short-chain polymer blending approach

Bottom-gate (BG) organic field-effect transistors (OFETs) play a crucial role in the development of flexible and printable electronics due to their ease of fabrication. However, their humidity sensitivity limits manufacturing conditions and raises production costs. Here, a facile approach is presented by blending organic semiconductors (OSCs) with a common insulating polymer, polystyrene (PS), to create water-stable BG OFETs, alongside an in-depth analysis of the underlying mechanism. The results reveal that blends formulated with short-chain-length PS markedly influence the structural dynamics and phase behavior of OSCs, resulting in a vertically phase-separated structure of PS-bottom and OSC-top formed. These improvements facilitate efficient charge transport and enhance moisture barriers in the channel. Consequently, the BG OFETs achieve improved device performance and water durability, even under boiling water. More importantly, the effectiveness of the blending approach has been validated across several representative OSC systems, demonstrating its potential for broadening the applicability of solution-processable organic electronics in challenging environmental conditions. © 2025 The Royal Society of Chemistry.