Document Type : Review Article

Authors

1 Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan, Iran.

2 Department of Physics, Faculty of Physics, University of Kashan, Kashan, Iran.

3 Faculty of Electrical and Computer Engineering, Qom University of Technology (QUT), Qom, Iran.

Abstract

All types of Light Emitting Diodes (LEDs) are desirable because of their widespread applications. The Quantum Dot-Based Light Emitting Diodes (QDLEDs) have a lot of unique properties attracting more attention. Predicting performance of QDLEDs can lead to a better and more efficient design of the device. In this paper, we have attempted to investigate the dependency of the device performance on the location of Quantum Dots (QDs) and determine the best location for the QDs in the QDLEDs. We use FDTD method to simulate and analysis the QDLEDs structure. The QDs are located in five different positions in TPBi layer then results are compared with each other. The results show that the closer the QDs to the hole transport layer (HTL), the better the luminescence. This improvement would be explained by two charge transport mechanisms including direct charge injection and exciton energy transfer. The results show that when the QDs are closer to the HTL, the device performance is better due to the greater balance of carriers.  In this condition holes can transfer from the HTL to the valence band easier.

Keywords

[1] S. Dayneko, D. Lypenko, P. Linkov, N. Sannikova, P. Samokhvalov, V. Nikitenko, and A. Chistyakov, “Application of CdSe/ZnS/CdS/ZnS core–multishell quantum dots to modern OLED technology,” Materials Today: Proceedings, Vol. 3, pp. 211-215, Jan. 2016.
[2] S. Dayneko, D. Lypenko, P. Linkov, A. Tameev, I. Martynov, P. S. Samokhvalov, and A. Chistyakov, “Effect of surface ligands on the performance of organic light-emitting diodes containing quantum dots,” In Optoelectronic Devices and Integration, Vol. 9270, pp. 927009, Oct. 2014.
[3] D. H. Emon, M. Kim, M. T. Sharbati, and H. K. Kim, “Injection of 2D electron gas into a quantum-dot organic light-emitting diode structure on silicon substrate,” Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena, Vol. 34, pp. 06KJ01, Nov. 2016.
[4] X. Yang, D. Zhao, K. S. Leck, S. T. Tan, Y. X. Tang, J. Zhao, H. V. Demir, and X. W. Sun, “Full visible range covering InP/ZnS nanocrystals with high photometric performance and their application to white quantum dot light‐emitting Diodes,” Advanced Materials, Vol. 24, pp. 4180-4185, Aug. 2012.
[5] Z. Hu, Y. Yin, M. U. Ali, W. Peng, S. Zhang, D. Li, T. Zou, Y. Li, S. Jiao, S. J. Chen, and C. Y. Lee, “Inkjet Printed Uniform Quantum Dots as Color Conversion Layers for Full-color OLED Displays,” Nanoscale, Dec. 2019.
[6] SONY ANNOUNCES 2013 BRAVIA TVS Sony. web.archive.org. 8 March 2013.
[7] W. Cao, C. Xiang, Y. Yang, Q. Chen, L. Chen, X. Yan, and L. Qian, “Highly stable QLEDs with improved hole injection via quantum dot structure tailoring,” Nature communications, Vol. 9, pp. 1-6, Jul. 2018.
[8] J. Song, O. Wang, H. Shen, Q. Lin, Z. Li, L. Wang, X. Zhang, and L. S. Li, “Over 30% External Quantum Efficiency Light‐Emitting Diodes by Engineering Quantum Dot‐Assisted Energy Level Match for Hole Transport Layer,” Advanced Functional Materials, Vol. 29, pp. 1808377, Aug. 2019.
[9] Z. Yang, Q. Wu, G. Lin, X. Zhou, W. Wu, X. Yang, J. Zhang, and W. Li, “All-solution processed inverted green quantum dot light-emitting diodes with concurrent high efficiency and long lifetime,” Materials Horizons, Vol. 6, pp. 2009-20, Aug. 2019.
[10] L. Wang, J. , Lin, Y. Hu, X. Guo, Y. Lv, Z. Tang, J. Zhao, Y. Fan, N. Zhang, Y. Wang, and X. Liu, “Blue quantum dot light-emitting diodes with high electroluminescent efficiency,” ACS applied materials & interfaces, Vol. 9, pp. 38755-38760, Nov. 2017.
[11] O. O. Matvienko, O. S. Kryzhanovska, Y. N. Savin, O. M. Vovk, N. V. Pogorelova, and V. V. Vashchenko, “Hybrid bulk and planar heterojunctions with electroluminescent quantum dots CdZnSeS and poly (dioctylfluorene),” Functional materials, Vol. 19, pp. 533-538, Sep. 2012.
[12] P. O. Anikeeva, C. F. Madigan, J. E. Halpert, M. G. Bawendi, and V. Bulović, “Electronic and excitonic processes in light-emitting devices based on organic materials and colloidal quantum dots,” Physical Review B, Vol. 78, pp. 085434, Aug. 2008.
[13] H. Zamani Siboni, B. Sadeghimakki, S. Sivoththaman, and H. Aziz, “Very High Brightness Quantum Dot Light-Emitting Devices via Enhanced Energy Transfer from a Phosphorescent Sensitizer,” ACS applied materials & interfaces, Vol. 7, pp. 25828-25834, Nov. 2015.
[14] K. S. Leck, Y. Divayana, D. Zhao, X. Yang, A.P. Abiyasa, E. Mutlugun, Y. Gao, S. Liu, S. T. Tan, X. W. Sun, and H. V. Demir, “Quantum dot light-emitting diode with quantum dots inside the hole transporting layers,” ACS applied materials & interfaces, Vol. 5, pp. 6535-6540, Jul. 2013.
[15] A. Tang, F. Teng, S. Xiong, Y. Wang, B. Feng, and Y. Hou, “Investigation on nanocrystals/polymer light-emitting diodes with different-sized water-sol CdSe nanocrystals,” Journal of The Electrochemical Society, Vol. 155, pp. K190-K194, Oct. 2008.
[16] A.W. Tang, F. Teng, Y. H. Gao, D. Li, S. L. Zhao, C. J. Liang, and Y. S. Wang, “White light emission from organic–inorganic hererostructure devices by using CdSe quantum dots as emitting layer,” Journal of luminescence, Vol. 122, pp. 649-651, Jan. 2007.
[17] P. O. Anikeeva, J. E. Halpert, M. G. Bawendi, and V. Bulovic, “Quantum dot light emitting device with electroluminescence tunable over the entire visible spectrum,” Nano Letter, Vol. 9, pp. 2532-2536, No. 2009.