Efficient and long‐life green light‐emitting diodes comprising tridentate thiol capped quantum dots

Abstract

In this paper, the green quantum dots capped with the ligand, tris(mercaptomethyl)nonane (TMMN), are fabricated as the light-emitting layer for efficient and bright light-emitting diodes. These TMMN-capped quantum dots exhibit well-preserved photoluminescence properties with quantum yields of ß90% after ligand exchange. The light-emitting diodes based on TMMN-capped quantum dots are reported with a maximum external quantum efficiency of 16.5% corresponding to a power efficiency and current efficiency of 57.6 lm W -1 and 70.1 cd A -1 , respectively. The devices exhibit high color stability that is not markedly affected by the increase of applied voltage, thus leading to a high color reproducibility. Most importantly, the devices exhibit high environmental stability. For the highest luminance devices (with emitting layer thickness of 25 nm) and the highest power efficiency devices (with emitting layer thickness of 38 nm), the lifetimes are > 480 000 h and > 110 000 h, respectively.

Transparent Conducting Electrodes for Quantum Dots Light Emitting Diodes

“…Li et al . reported green QDLEDs using commercial ITO as the bottom electrode; all of the devices were fabricated on ultrasonically cleaned ITO‐coated glass (15 Ohm/square).…”

“…Li et al [54] reported green QDLEDs using commercial ITO as the bottom electrode; all of the devices were fabricated on ultrasonically cleaned ITO-coated glass (15 Ohm/square). The authors employed a solution-processed, multilayer device architecture ( Figure 4a that blue QDLEDs based on TMMN-capped quantum dots have a maximum external quantum efficiency of 16.5 %, corresponding to power and current efficiencies of 57.6 lm/W and 70.1 cd/A (Figure 4c), respectively.…”

“…Since the first demonstration of them, there have been rapid advances in QDLED performance and fabrication processes, comparable with that of current LCDs and OLEDs. Blue, green, and red QDLEDs have demonstrated peak external quantum efficiency (EQE) of 12, 16.5, and 20 %, respectively . Among several layers and components in QDLEDs, electrical, optical, and morphological properties of transparent conducting electrodes (TCEs) critically influence their performance and reliability, including that of flexible QDLEDs.…”

“…Blue, green, and red QDLEDs have demonstrated peak external quantum efficiency (EQE) of 12,16.5, and 20 %, respectively. [7][8][9] Among several layers and components in QDLEDs, electrical, optical, and morphological properties of transparent conducting electrodes (TCEs) critically influence their performance and reliability, including that of flexible QDLEDs. As shown in Figure 1, whether a normal or an inverted QDLED, a high-quality TCE anode or cathode patterned on substrate is necessary.…”

Introductory Chapter: Quantum-Dots Based Organic Light- Emitting Diodes - The State-of-the-Art

“…Finally yet importantly, QD-LEDs are cheaper than OLEDs. Nowadays, researches try to improve eiciency of passing light through the quantum dot crystals, which can help the QD-LEDs performance [3]. QD-LEDs have some unique features such as beter color accuracy, higher brightness, more stable performance and lower cost.…”