Tracing the electron transport behavior in quantum-dot light-emitting diodes via single photon counting technique

• Published in: Nature communications Vol. 15; no. 1; pp. 8150 - 10
• Main Authors: Su, Qiang, Chen, Zinan, Chen, Shuming
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 17.09.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 639/624/1020/1089; 639/624/399/1017; Electroluminescence; Electron transport; Energy conversion efficiency; Humanities and Social Sciences; Leakage; Light emitting diodes; Luminescence; multidisciplinary; Photoluminescence; Photons; Quantum dots; Science; Science (multidisciplinary); Transport phenomena
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-52521-0

The electron injection and transport behavior are of vital importance to the performance of quantum-dot light-emitting diodes. By simultaneously measuring the electroluminescence-photoluminescence of the quantum-dot light-emitting diodes, we identify the presence of leakage electrons which leads to the discrepancy of the electroluminescence and the photoluminescence roll-off. To trace the transport paths of the leakage electrons, a single photon counting technique is developed. This technique enables us to detect the weak photon signals and thus provides a means to visualize the electron transport paths at different voltages. The results show that, the electrons, except those recombining within the quantum-dots, leak to the hole transport layer or recombine at the hole transport layer/quantum-dot interface, thus leading to the reduction of efficiency. By reducing the amount of leakage electrons, quantum-dot light-emitting diode with an internal power conversion efficiency of over 98% can be achieved. Su et al. report a single photon counting technique to trace the electron transport paths at different voltages for QLEDs, revealing the leakage electrons into the hole transport layer or recombination at the interface, providing unambiguous understanding in the device operation and degradation mechanism.