Double Metal Oxide Electron Transport Layers for Colloidal Quantum Dot Light-Emitting Diodes

• Published in: Nanomaterials (Basel, Switzerland) Vol. 10; no. 4; p. 726
• Main Authors: Park, Myeongjin, Roh, Jeongkyun, Lim, Jaehoon, Lee, Hyunkoo, Lee, Donggu
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI 11.04.2020; MDPI AG
• Subjects: Communication; double electron transport layer (ETL); light emitting diode (LED); metal oxide; quantum dot (QD); SnO2 nanoparticles; quantum dot (QD); light emitting diode (LED); SnO2 nanoparticles; double electron transport layer (ETL); metal oxide
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano10040726

The performance of colloidal quantum dot light-emitting diodes (QD-LEDs) have been rapidly improved since metal oxide semiconductors were adopted for an electron transport layer (ETL). Among metal oxide semiconductors, zinc oxide (ZnO) has been the most generally employed for the ETL because of its excellent electron transport and injection properties. However, the ZnO ETL often yields charge imbalance in QD-LEDs, which results in undesirable device performance. Here, to address this issue, we introduce double metal oxide ETLs comprising ZnO and tin dioxide (SnO ) bilayer stacks. The employment of SnO for the second ETL significantly improves charge balance in the QD-LEDs by preventing spontaneous electron injection from the ZnO ETL and, as a result, we demonstrate 1.6 times higher luminescence efficiency in the QD-LEDs. This result suggests that the proposed double metal oxide ETLs can be a versatile platform for QD-based optoelectronic devices.