Visible‐Light Photoprogrammable Transistors Enabled by an All‐Organic Triplet‐Sensitized Diarylethene Channel Layer

ABSTRACT Light‐programmable transistors are promising for next‐generation electronics, but their reliance on high‐energy UV light undermines stability and safety. Here, we demonstrate visible‐light‐only photoprogramming of organic field‐effect transistors (OFETs) by integrating an all‐organic triplet‐sensitized diarylethene system into the channel layer. Rather than redesigning the photoswitch, this modular additive strategy renders a conventional UV‐responsive diarylethene visible‐addressable in solid‐state transistors. A ternary blend of a polymer semiconductor (DPP‐DTT), a diarylethene photoswitch (DAE‐HP), and an organic triplet sensitizer (4CzIPN) enables fully reversible current modulation via photocyclization at 450 nm and photocycloreversion at 520 nm. The devices achieve a switching ratio up to 2.8 × 10 3 and remain stable over 100 cycles. Mechanistic studies show that DAE‐HP and 4CzIPN co‐localize within amorphous domains without perturbing polymer crystallinity, maintaining charge‐transport continuity while ensuring the short‐range proximity required for triplet exchange. Transient absorption spectroscopy supports efficient triplet–triplet energy transfer (TTET) from 4CzIPN to DAE‐HP as the driver of visible‐light photoswitching. These results identify nanoscale organization as the key lever for UV‐free operation and provide a practical blueprint for safer, durable, and solution‐processable light‐programmable organic electronics.