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.

Vertical organic transistors with short channels for multifunctional optoelectronic devices

“…In this framework, non-volatile light-emitting device and long afterglow light-emitting device were successfully demonstrated by our group via embedding photochromic molecules and metal oxides exhibiting persistent photoconductivity, respectively. 98,99 By mastering such a hybrid approach, the fabrication multifunctional devices with short vertical channels will lay the foundations for new emerging optoelectronic devices for memory displays and visual sensors.…”

A robust vertical nanoscaffold for recyclable, paintable, and flexible light-emitting devices

“…SP images were collected with Pt/Ir-coated silicon probes (Bruker SCM-PIT-V2; resonant frequency ≈ 75 kHz, k ≈ 3 N m −1 ) at ambient conditions in the amplitude modulation mode. The J/L - V characteristics and efficiencies were measured using a Keithley 2636A Source Meter, and the irradiation intensity of the devices was measured by a photodiode (Hamamatsu S3204-08), which has been previously calibrated by a luminance meter (Konica Minolta, LS-100) ( 42 , 43 ).…”

Bio-Inspired Electronic Eyes and Synaptic Photodetectors for Mobile Artificial Vision

“…Furthermore, the addition of unconventional functions to the electronic eyes is desired. For example, the detection of invisible (e.g., infrared [90]- [92] and ultraviolet [93], [94]) and/or circularly polarized light [95]- [97] can provide image-based information that cannot be detected by human eyes. These properties would be useful for particular applications such as night vision [98] and gas leakage detection [99].…”