Enhancement of Stability to Light in Field-Effect Transistors Based on Cumulenic sp-carbon Wires by Opaque Gating Electrodes

Cumulenic sp-hybridized carbon wires are receiving attention both for their excellent intrinsic electronic properties and for their potential exploitation as active semiconducting layers in large-area and flexible organic electronic devices. Such molecules exhibit a highly conjugated backbone chain, an equally high degree of electronic tunability, and offer an opportunity to better understand the elusive carbon allotrope known as carbyne. Among this class of molecules, tetraphenyl[3]cumulene ([3]Ph) has emerged as a reference point for applications in organic field-effect transistors (OFETs), owing to promising charge carrier mobility of > 0.1 cm2/Vs. However, photoinduced degradation of [3]Ph is a significant limitation to its possible future applications. Here, a gating strategy based on an opaque, spray-coated activated carbon (AC) based electrode is investigated to mitigate photodegradation in [3]Ph-based OFETs. Top-gate bottom-contact transistors have been fabricated and tested under various light conditions, comparing devices gated either by a transparent layer of PEDOT:PSS or opaque layers of AC, to probe light-induced degradation. Unlike PEDOT:PSS devices, the AC-gated transistors maintain consistent performance under light, demonstrating potential for practical applications of [3]Ph, similar cumulenes or even other photodegradable semiconductors in organic electronics.