Atomic Layer Deposition Stabilizes Nanocrystals, Enabling Reliably High-Performance Quantum Dot LEDs

Haoyue Wan; Pan Xia; Euidae Jung; Muhammad Imran; Ruiqi Zhang; Yiqing Chen; Julian A. Steele; Sabah Gaznaghi; Yanjiang Liu; Ya Kun Wang; Lianzhou Wang; Yu Ho Won; Kwang Hee Kim; Vladimir Bulović; Sjoerd Hoogland; Edward H. Sargent

doi:10.1002/adma.202418300

Atomic Layer Deposition Stabilizes Nanocrystals, Enabling Reliably High-Performance Quantum Dot LEDs

Haoyue Wan, Pan Xia, Euidae Jung, Muhammad Imran, Ruiqi Zhang, Yiqing Chen, Julian A. Steele, Sabah Gaznaghi, Yanjiang Liu, Ya Kun Wang, Lianzhou Wang, Yu Ho Won, Kwang Hee Kim, Vladimir Bulović^*, Sjoerd Hoogland, Edward H. Sargent^*

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

Abstract

Quantum dot light-emitting diodes (QD-LEDs) with stable high efficiencies are crucial for next-generation displays. However, uncontrollable aging, where efficiency initially increases during storage (positive aging) but is entirely lost upon extended aging (negative aging), hinders further device development. It is uncovered that it is chemical changes to nanocrystal (NC)-based electron transport layer (ETL) that give rise to positive aging, their drift in structure and morphology leading to transiently improved charge injection balance. Using grazing-incidence small-angle X-ray scattering, it is found that ZnMgO NCs undergo size-focusing ripening during aging, improving size uniformity and creating a smoother energy landscape. Electron-only device measurements reveal a sevenfold reduction in trap states, indicating enhanced surface passivation of ZnMgO. These insights, combined with density functional theory calculations of ZnMgO surface binding, inspire an atomic layer deposition (ALD) strategy with Al₂O₃ to permanently suppress surface traps and inhibit NC growth, effectively eliminating aging-induced efficiency loss. This ALD-engineered ZnMgO ETL enables reproducible external quantum efficiencies (EQEs) of 17% across 30 batches of LEDs with a T₆₀ of 60 h at an initial luminance of 4500 cd m⁻², representing a 1.6-fold increase in EQE and a tenfold improvement in operating stability compared to control devices.

Original language	English (US)
Article number	2418300
Journal	Advanced Materials
Volume	37
Issue number	11
DOIs	https://doi.org/10.1002/adma.202418300
State	Published - Mar 19 2025

Funding

H.W., P.X., and E.J. contributed equally to this work. The authors thank Remi Wolowiec, Damir Kopilovic, Larissa Levina, and Elenita Palmiano for their assistance throughout the study. Part of the research described in this paper was performed at the University of Toronto's Open Centre for the Characterization of Advanced Materials (OCCAM). The authors gratefully acknowledge funding from Samsung Electronics Co. (MRA 211815). J.A.S. acknowledges financial support from the Australian Research Council (DE230100173) and L.W. is grateful for the support provided through the ARC Laureate Fellowship scheme (FL190100139). A portion of this research was undertaken on the SAXS/WAXS beamline at the Australian Synchrotron, part of ANSTO (grant no. M20652).

Keywords

ZnMgO nanoparticles
atomic layer deposition
electron transport layer
light-emitting diodes
quantum dots

ASJC Scopus subject areas

General Materials Science
Mechanics of Materials
Mechanical Engineering

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10.1002/adma.202418300

Cite this

Wan, H., Xia, P., Jung, E., Imran, M., Zhang, R., Chen, Y., Steele, J. A., Gaznaghi, S., Liu, Y., Wang, Y. K., Wang, L., Won, Y. H., Kim, K. H., Bulović, V., Hoogland, S., & Sargent, E. H. (2025). Atomic Layer Deposition Stabilizes Nanocrystals, Enabling Reliably High-Performance Quantum Dot LEDs. Advanced Materials, 37(11), Article 2418300. https://doi.org/10.1002/adma.202418300

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title = "Atomic Layer Deposition Stabilizes Nanocrystals, Enabling Reliably High-Performance Quantum Dot LEDs",

abstract = "Quantum dot light-emitting diodes (QD-LEDs) with stable high efficiencies are crucial for next-generation displays. However, uncontrollable aging, where efficiency initially increases during storage (positive aging) but is entirely lost upon extended aging (negative aging), hinders further device development. It is uncovered that it is chemical changes to nanocrystal (NC)-based electron transport layer (ETL) that give rise to positive aging, their drift in structure and morphology leading to transiently improved charge injection balance. Using grazing-incidence small-angle X-ray scattering, it is found that ZnMgO NCs undergo size-focusing ripening during aging, improving size uniformity and creating a smoother energy landscape. Electron-only device measurements reveal a sevenfold reduction in trap states, indicating enhanced surface passivation of ZnMgO. These insights, combined with density functional theory calculations of ZnMgO surface binding, inspire an atomic layer deposition (ALD) strategy with Al₂O₃ to permanently suppress surface traps and inhibit NC growth, effectively eliminating aging-induced efficiency loss. This ALD-engineered ZnMgO ETL enables reproducible external quantum efficiencies (EQEs) of 17% across 30 batches of LEDs with a T60 of 60 h at an initial luminance of 4500 cd m−2, representing a 1.6-fold increase in EQE and a tenfold improvement in operating stability compared to control devices.",

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AU - Xia, Pan

AU - Jung, Euidae

AU - Imran, Muhammad

AU - Zhang, Ruiqi

AU - Chen, Yiqing

AU - Steele, Julian A.

AU - Gaznaghi, Sabah

AU - Liu, Yanjiang

AU - Wang, Ya Kun

AU - Wang, Lianzhou

AU - Won, Yu Ho

AU - Kim, Kwang Hee

AU - Bulović, Vladimir

AU - Hoogland, Sjoerd

AU - Sargent, Edward H.

PY - 2025/3/19

Y1 - 2025/3/19

N2 - Quantum dot light-emitting diodes (QD-LEDs) with stable high efficiencies are crucial for next-generation displays. However, uncontrollable aging, where efficiency initially increases during storage (positive aging) but is entirely lost upon extended aging (negative aging), hinders further device development. It is uncovered that it is chemical changes to nanocrystal (NC)-based electron transport layer (ETL) that give rise to positive aging, their drift in structure and morphology leading to transiently improved charge injection balance. Using grazing-incidence small-angle X-ray scattering, it is found that ZnMgO NCs undergo size-focusing ripening during aging, improving size uniformity and creating a smoother energy landscape. Electron-only device measurements reveal a sevenfold reduction in trap states, indicating enhanced surface passivation of ZnMgO. These insights, combined with density functional theory calculations of ZnMgO surface binding, inspire an atomic layer deposition (ALD) strategy with Al₂O₃ to permanently suppress surface traps and inhibit NC growth, effectively eliminating aging-induced efficiency loss. This ALD-engineered ZnMgO ETL enables reproducible external quantum efficiencies (EQEs) of 17% across 30 batches of LEDs with a T60 of 60 h at an initial luminance of 4500 cd m−2, representing a 1.6-fold increase in EQE and a tenfold improvement in operating stability compared to control devices.

AB - Quantum dot light-emitting diodes (QD-LEDs) with stable high efficiencies are crucial for next-generation displays. However, uncontrollable aging, where efficiency initially increases during storage (positive aging) but is entirely lost upon extended aging (negative aging), hinders further device development. It is uncovered that it is chemical changes to nanocrystal (NC)-based electron transport layer (ETL) that give rise to positive aging, their drift in structure and morphology leading to transiently improved charge injection balance. Using grazing-incidence small-angle X-ray scattering, it is found that ZnMgO NCs undergo size-focusing ripening during aging, improving size uniformity and creating a smoother energy landscape. Electron-only device measurements reveal a sevenfold reduction in trap states, indicating enhanced surface passivation of ZnMgO. These insights, combined with density functional theory calculations of ZnMgO surface binding, inspire an atomic layer deposition (ALD) strategy with Al₂O₃ to permanently suppress surface traps and inhibit NC growth, effectively eliminating aging-induced efficiency loss. This ALD-engineered ZnMgO ETL enables reproducible external quantum efficiencies (EQEs) of 17% across 30 batches of LEDs with a T60 of 60 h at an initial luminance of 4500 cd m−2, representing a 1.6-fold increase in EQE and a tenfold improvement in operating stability compared to control devices.

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Atomic Layer Deposition Stabilizes Nanocrystals, Enabling Reliably High-Performance Quantum Dot LEDs

Abstract

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Keywords

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