Synaptic Plasticity Powering Long‐Afterglow Organic Light‐Emitting Transistors

Abstract Long‐lasting luminescence in optoelectronic devices is highly sought after for applications in optical data storage and display technology. While in light‐emitting diodes this is achieved by exploiting long‐afterglow organic materials as active components, such a strategy has never been pursued in light‐emitting transistors, which are still rather unexplored and whose technological potential is yet to be demonstrated. Herein, the fabrication of long‐afterglow organic light‐emitting transistors (LAOLETs) is reported whose operation relies on an unprecedented strategy based on a photoinduced synaptic effect in an inorganic indium‐gallium‐zinc‐oxide (IGZO) semiconducting channel layer, to power a persistent electroluminescence in organic light‐emitting materials. Oxygen vacancies in the IGZO layer, produced by irradiation at λ = 312 nm, free electrons in excess yielding to a channel conductance increase. Due to the slow recombination kinetics of photogenerated electrons to oxygen vacancies in the channel layer, the organic material can be fueled by postsynaptic current and displays a long‐lived light‐emission (hundreds of seconds) after ceasing UV irradiation. As a proof‐of‐concept, the LAOLETs are integrated in active‐matrix light‐emitting arrays operating as visual UV sensors capable of long‐lifetime green‐light emission in the irradiated regions.