Charge Transport in Blue Quantum Dot Light‐Emitting Diodes

• Published in: Advanced electronic materials Vol. 10; no. 11
• Main Authors: Li, Shuxin, Lin, Wenxin, Feng, Haonan, Blom, Paul W. M., Huang, Jiangxia, Li, Jiahao, Lin, Xiongfeng, Guo, Yulin, Liang, Wenlin, Wu, Longjia, Niu, Quan, Ma, Yuguang
• Format: Journal Article
• Language: English
• Published: Wiley-VCH 01.11.2024
• Subjects: blue quantum dots; extended Gaussian disorder model; hopping transport; trap‐free space‐charge‐limited current
• ISSN: 2199-160X; 2199-160X
• DOI: 10.1002/aelm.202400142

Although quantum dot light‐emitting diodes (QLEDs) are extensively studied nowadays, their charge transport mechanism remains a subject of ongoing debate. Here, the hole transport in blue quantum dots (QDs) (CdZnSe/ZnSe/ZnS/CdZnS/ZnS based) is investigated by combining current‐voltage and transient electroluminescence measurements. The study demonstrates that the hole transport in QD thin films is characterized by a trap‐free space‐charge‐limited current with a zero‐field room temperature mobility of 4.4 × 10−11 m2 V−1 s−1. The zero‐field hole mobility is thermally activated with an activation energy of 0.30 eV. Applying the Extended Gaussian Disorder model provides a consistent description of the QD hole current as a function of voltage and temperature. The QD hole mobility is characterized by a hopping distance of 2.8 nm in a Gaussian broadened density of states with a width of 0.12 eV. Quantum dot semiconductor is a disordered system in which hole transport occurs via a hopping way. During the transport process, hole carriers hop between localized sites that exhibit a Gaussian distribution. In this study, the hole transport mechanism in quantum dots is investigated using single‐carrier devices. The study employs the EGDM model to provide a quantitative analysis of this transport behavior.