Highly Efficient Light‐Emitting Diodes Based on Self‐Assembled Colloidal Quantum Wells

Abstract

Nanocrystal‐based light‐emitting diodes (Nc‐LEDs) have immense potential for next‐generation high‐definition displays and lighting applications. They offer numerous advantages, such as low cost, high luminous efficiency, narrow emission, and long lifetime. However, the external quantum efficiency (EQE) of Nc‐LEDs, typically employing isotropic nanocrystals, has been limited by the out‐coupling factor. Here we demonstrate efficient, bright, and long lifetime red Nc‐LEDs based on anisotropic nanocrystals of colloidal quantum wells (CQWs). Through modification of the substrate's surface properties and control of the interactions among CQWs, we successfully spin‐coated a self‐assembled layer with an exceptionally high distribution of in‐plane transitions dipole moment (TDM) of 95%, resulting in an out‐coupling factor of 37%. Our devices exhibit a remarkable peak external quantum efficiency (EQE) of 26.9%, accompanied by a maximum brightness of 55,754 cd m−2 and a long operational lifetime (T95@100 cd m−2) over 15,000 h. These achievements represent a significant advancement compared to previous studies on Nc‐LEDs incorporating anisotropic nanocrystals. We expect our work to provide a general self‐assembly strategy for enhancing the light extraction efficiency of Nc‐LEDs based on anisotropic nanocrystals.This article is protected by copyright. All rights reserved

High-Efficiency and Stable Colloidal One-Dimensional Core/Shell Nanorod Light-Emitting Diodes

“… ,, As shown in Figure e–g, the film of CdSe/CdZnS/ZnS NRs exhibited a higher in-plane TDM distribution of 90% compared to that of the film of CdSe/CdS NRs (83%). The result is close to the highest reported values of colloidal quantum wells (95%) …”

“…The result is close to the highest reported values of colloidal quantum wells (95%). 55 The NR-LEDs based on CdSe/CdZnS/ZnS NRs were fabricated with a glass/ITO/PEDOT:PSS/poly-TPD/NRs/ ZnMgO/Al device structure (Figure 5a). The cross-sectional TEM image of the NR-LED is illustrated in Figure S6.…”

Gradient Alloy Shell Enabling Colloidal Quantum Wells Light-Emitting Diodes with Efficiency Exceeding 22%

“…The acceleration factor, n, is approximately 1.75 according to the reference. 50 The measured T 95 @1,000 cd/m 2 is approximately 116 h. Thus, the estimated T 95 @100 cd/m 2 is over 65,00 h, demonstrating excellent operation stability. The average EQE of 25 devices is 20.48%, demonstrating good reproducibility (Figure 5f).…”

“…The results are fitted by an empirical equation, ( L 0 ) n × T 95 = constant, where L 0 , n , and T 95 are initial brightness, acceleration factor, and lifetime (the time required for the luminance to decrease to 95% L 0 ), respectively. The acceleration factor, n , is approximately 1.75 according to the reference . The measured T 95 @1,000 cd/m 2 is approximately 116 h. Thus, the estimated T 95 @100 cd/m 2 is over 65,00 h, demonstrating excellent operation stability.…”