Optimum Design Configuration of Thin‐Film Transistors and Quantum‐Dot Light‐Emitting Diodes for Active‐Matrix Displays

Abstract

Active matrix (AM) quantum‐dot light‐emitting diodes (QLEDs) driven by thin‐film transistors (TFTs) have attracted significant attention for use in next‐generation displays. Several challenges remain for the realisation of AM‐QLEDs, such as device design, fabrication process, and integration between QLEDs and TFTs, depending on their device structures and configurations. Herein, we demonstrate efficient and stable AM‐QLEDs using conventional and inverted structured QLEDs (C‐ and I‐QLEDs, respectively) combined with facile type‐convertible (p‐ and n‐type) single‐walled carbon nanotube (SWNT)‐based TFTs. Based on the four possible configurations of the QLED–TFT subpixel, we compare the performance of the SWNT TFT‐driven QLEDs and the fabrication process to determine the ideal configuration, taking advantage of each structure for AM‐QLEDs. We also optimise the QLEDs and TFTs to maximise the performance of the AM‐QLEDs—the inner shell composition of quantum dots and carrier type of TFTs—resulting in a maximum external quantum efficiency and operational lifetime (at an initial luminance of 100 cd/m2) of 21.2% and 38,100,000 h for the C‐QLED, and 19.1% and 133,100,000 h for the I‐QLED, respectively. Finally, we successfully demonstrate a 5×5 AM‐QLED display array controlled using SWNT TFTs. This study is expected to contribute to the development of advanced AM‐QLED displays.This article is protected by copyright. All rights reserved

Fully solution-processed red tandem quantum dot light-emitting diodes with an EQE exceeding 35%

“…The conventional structure can be manufactured using mature solution processes, resulting in better economic benefits and providing good luminescence efficiency and stability. 7,27 TFB is a commonly used polymer hole-transporting material (HTM) with higher mobility (∼10 −3 cm 2 V −1 s −1 ) than other HTMs. Red QLEDs employing TFB as the HTL have demonstrated good performance in the literature with low turn-on voltage and high EQE.…”

Active-Matrix Array Based on Thin-Film Transistors Using Emerging Materials for Application: From Lab to Industry

“…(d) Cross-sectional schematic diagram of a TFT-µ-LED pixel integrated t flip chip bonding (adapted from [63] with permission from John Wiley and Sons). (e) Dr flexible OLED display based on a backplane circuit composed of MoS2 attached to a huma (adapted from [64] with permission from American Association for the Advancement of S (f) Four different configurations to compare the characteristics of each combination of QLED ture and CNT TFT type (adapted from [65] with permission from John Wiley and Sons).…”

“…Baek et al implemented a CNT TFT-based active-matrix QLED display [65]. In particular, to investigate the optimum design for a high-performance QLED array, they compared the characteristics of a total of four types of QLED arrays according to the type of driving TFT (p-or n-type) and the connection configuration between QLED and the driving transistor (conventional QLED or inverted QLED) (Figure 2f).…”

“…They passivated Si 3 N 4 on p-type CNT TFT to prepare n-type CNT TFT. The conversion of CNT TFT to n-type operation through Si 3 N 4 passivation is because the positive fixed charge in Si 3 N 4 causes ntype doping and protects it from atmospheric oxygen and water, which cause p-type doping effects [65,66]. Subsequently, the distinction between conventional QLED and inverted QLED was defined based on whether the upper Al and lower ITO electrodes served as cathode/anode or anode/cathode, respectively.…”

Memristive Switching Mechanism in Colloidal InP/ZnSe/ZnS Quantum Dot-Based Synaptic Devices for Neuromorphic Computing

“…Typically, neuromorphic computing architectures that can emulate the biological brain are generally composed of either two-terminal devices, such as resistive random-access memory (RAM), phase change RAM, or conductive bridge RAM, or three-terminal-based field-effect transistors. , In particular, two-terminal memristive devices using metal oxides, − two-dimensional materials, polymers, and colloidal quantum dots (QDs) − have been considered promising electronic devices due to their high areal density, scalability, and adjustable conductance. Among these candidates, core/shell-structured colloidal QDs are advantageous because of their electronic properties can be tuned by modifying the size, chemical composition, and surfactant. − They also show excellent versatility on various substrates (from rigid to flexible), with solution processability and high stability compared to those of organic semiconductors. ,− Furthermore, QDs are highly sensitive to light, allowing synaptic input of both electrical and optical signals into the device . Despite their excellent electrical and optical properties, the mechanism behind the resistive switching (RS) in QD memristors has not been fully elucidated due to the considerable challenge of deterministically monitoring the location and quantity of defects in QDs.…”