Alternating‐Current‐Driven Color‐Tunable Organic Light‐Emitting Triodes

Abstract

lighting panels incorporate light-emitting units that are controlled by a separate backplane of transistors; [2] such complexity and high cost limit their large-scale implementation. The challenge exists to develop new device configurations that simultaneously offer efficient light emission and effective operational control without employing any backplane circuitry, thereby simplifying the fabrication process and lowering the cost. In this scenario, smart devices-for example, organic light-emitting transistors (OLETs) that demonstrate both electroluminescence (EL) and control functions in a single unit-have attracted the attention of both academia and industry. [3] Depending on their structures, OLETs are categorized into two general types: singlelayer and multilayer OLETs. Although single-layer OLETs typically have the preferred device architecture, because of their capability to display carrier transport and light emission from a single active layer, it is quite difficult for conventional materials and device configurations to provide both of these objectives simultaneously. [4] In multilayer OLETs, separate carrier-transport and light-emitting layers can lead to good luminous efficiencies; [5] however, the complexity and high cost of fabricating such devices have hindered their further development. In addition to exploring miniaturized devices having simple architectures, the ability to adjust the emission spectrum and intensity of organic light-emitting diodes (OLEDs) is also crucial to the realization of well-controlled displays; two approaches have been adopted widely: 1) voltage-dependent emission shifting [6][7][8][9] and 2) the stacking of tandem [10][11][12][13][14][15][16][17][18] multiple monochrome light-emitting units or aligning them side-by-side. [19][20][21] Nonetheless, the brightness of a device is compromised when tuning its emission spectrum or intensity with respect to the voltage, and the complicated protocols necessary for fabricating multiple light-emitting units pose major challenges. Considering the aforementioned technical issues, there remains much room to explore new multifunctional device configurations with well-controlled operation.Current state-of-the-art lighting devices are mostly driven by direct current (DC) and therefore require additional back-end electronics (e.g., power converters and rectifiers) while integrating into household electric systems that typically comprise Exploring multifunctional, miniaturized light-emitting devices with well-controlled operation is deemed vital to meet the increasing demands of full-color displays and lighting systems. Nevertheless, complicated architectures, low performance, and poor operational control remain daunting challenges in the realization of smart devices. Here, an alternating-current-driven organic light-emitting triode (AC-OLETr) is reported with simple yet versatile architecture that emits light with precise control over the color and intensity. The fabricated AC-OLETr devices are driven and regulated by a three-phase AC supp...

Asymmetrically Enhanced Coplanar‐Electrode Electroluminescence for Information Encryption and Ultrahighly Stretchable Displays

“…By incorporating organic emitters and quantum dots, coplanar-electrode AC-driven organic light-emitting diodes (OLEDs) [15] and quantum-dot light-emitting diodes (QLEDs) [34] were developed respectively. The device format was further advanced to produce AC-driven color-tunable organic lightemitting triodes, [12] and three-phase electric power-driven EL devices. [15] A series of works on visualizing impedance, [35] pressure, [36] liquid, [37] magnetic, [22] and temperature sensors [38] based on coplanar-electrode AC-EL devices were reported successively.…”

“…[8] With the rapid development of communication technology and mankind's pursuit of colorful and practical display equipment, EL devices are now evolving in the direction of multifunctionality and digitalization. [5,[9][10][11] Compared with the direct-current-driven EL (DC-EL) devices, the alternating-currentdriven EL (AC-EL) counterparts possess the promising attributes of frequency-and phase-tunable emission, [12] effective avoidance of charge accumulation, [13] prevention of electrochemical reactions between electrodes and the emissive layer, [14] and facile integration with household power supply, [15] contributing to multifunctional features with prolonged operational lifetime, friendly installation and energy saving.…”

“…[8] With the rapid development of communication technology and mankind's pursuit of colorful and practical display equipment, EL devices are now evolving in the direction of multifunctionality and digitalization. [5,[9][10][11] Compared with the direct-current-driven EL (DC-EL) devices, the alternating-currentdriven EL (AC-EL) counterparts possess the promising attributes of frequency-and phase-tunable emission, [12] effective avoidance of charge accumulation, [13] prevention of electrochemical reactions between electrodes and the emissive layer, [14] and facile integration with household power supply, [15] contributing to multifunctional features with prolonged operational lifetime, friendly installation and energy saving.Among AC-EL devices, AC-based thinfilm EL (AC-TFEL) variants offer to captivate characteristics in various aspects, such as facile and convenient large-area processability [16] along with excellent mechanical and environmental durability, [17] etc. [18] Through the design of new device formats and the introduction of functional materials, several features have been successfully implemented in the devices, including wearable display, [19] information encryption, [20] visualized sensing, [21] soft robots, [8] and motion tracking.…”

Recent Progress in AC-Driven Organic and Perovskite Electroluminescent Devices

“…Copyright 2018 John Wiley and Sons. (f, g) Reprinted with permission from ref . Copyright 2021 John Wiley and Sons.…”

Bright Stretchable White Alternating‐Current Electroluminescent Devices Enabled by Photoluminescent Phosphor

“…[34] Recently, we reported an effective method to realize efficient color-tunable ACEL by simply adjusting the AC phase difference. [35] However, these multifunctional devices are attained at the expense of complex structures and complicated driving circuits. Despite all of the aforementioned research achievements, developing more simple and efficient approaches for the fabrication of white ACEL displays still remains a challenge.…”