Capillary Tube-Assisted Melt Processing for Ultrafast, Solvent-Free, and Vacuum-Free Formation of Autopassivated Organic Semiconductors

In recent decades, research on organic field-effect transistors (OFETs) has primarily focused on enhancing their electrical performance through various fabrication strategies. However, the performance of these devices without passivation layers often degrades significantly when exposed to ambient air and moisture, highlighting the need for effective passivation. This work proposes an efficient method for fabricating autopassivated organic semiconductor films via a capillary tube-assisted rolling process that induces spontaneous phase separation in the active layer during semiconductor layer deposition. This process utilizes tetratetracontane (TTC, C44H90) as a dual-function material, which acts as both a passivation layer and a melt-processable solvent, and 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene), a solution-processable p-type organic semiconductor. The capillary tube-assisted rolling process facilitates in situ vertical separation, wherein TIPS-pentacene forms an active semiconductor layer at the bottom; meanwhile, TTC spontaneously segregates at the top surface, forming a uniform passivation layer. The hydrophobic nature of TTC effectively protects the semiconductor film from environmental degradation. Additionally, the rolling process induces a directional crystallization of TIPS-pentacene under a controlled thermal gradient. Performance of device stored in ambient air (25 °C) and in a controlled climatic chamber (25 °C and 95% RH) remained stable under both conditions, demonstrating that the TTC layer effectively protected TIPS-pentacene from degradation caused by moisture and oxygen. The obtained results highlight the potential applicability of this melt-based self-passivating fabrication strategy as a platform for next-generation organic electronics with other organic semiconductors and flexible or stretchable electronics.