Efficient Cadmium-Free Inverted Red Quantum Dot Light-Emitting Diodes

Chae Young Lee; Nagarjuna Naik Mude; Raju Lampande; Kwan Ju Eun; Ji Eun Yeom; Hyung Sik Choi; Sang Hyun Sohn; Jun Mo Yoo; Jang Hyuk Kwon

doi:10.1021/acsami.9b12514

Efficient Cadmium-Free Inverted Red Quantum Dot Light-Emitting Diodes

Chae Young Lee, Nagarjuna Naik Mude, Raju Lampande, Kwan Ju Eun, Ji Eun Yeom, Hyung Sik Choi, Sang Hyun Sohn, Jun Mo Yoo, Jang Hyuk Kwon

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

47 Citations (Scopus)

Abstract

Here, we report an efficient inverted red indium phosphide (InP) comprising QD (InP/ZnSe/ZnS, core/shell structure) light-emitting diode (QLED) by modulating an interfacial contact between the electron transport layer and emissive InP-QDs and applying self-aging approach. The red InP-QLED with optimized interfacial contact exhibits a significant improvement in maximum external quantum efficiency and current efficiency from 4.42 to 10.2% and 4.70 to 10.8 cd/A, respectively, after 69 days of self-aging, which is an almost 2.3-fold improvement compared to the fresh device. The analysis indicates the consecutive reduction in electron injection and accumulation in the emissive QD due to changes in the conduction band minimum of ZnMgO (0.1 eV after 10 days of storage) through a downward vacuum-level shift according to the aging times. During the device aging periods, the oxygen vacancy of ZnMgO reduces, which leads to lower the conductivity of ZnMgO. As a result, charge balance of the device is improved with the suppression of exciton quenching at the interface of ZnMgO and InP-QD.

Original language	English
Pages (from-to)	36917-36924
Number of pages	8
Journal	ACS applied materials & interfaces
Volume	11
Issue number	40
DOIs	https://doi.org/10.1021/acsami.9b12514
Publication status	Published - 9 Oct 2019

Bibliographical note

Publisher Copyright:
© 2019 American Chemical Society.

Keywords

cadmium-free quantum dots
charge balance
charge carrier injection layers
inverted structure
light-emitting diode

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10.1021/acsami.9b12514

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title = "Efficient Cadmium-Free Inverted Red Quantum Dot Light-Emitting Diodes",

abstract = "Here, we report an efficient inverted red indium phosphide (InP) comprising QD (InP/ZnSe/ZnS, core/shell structure) light-emitting diode (QLED) by modulating an interfacial contact between the electron transport layer and emissive InP-QDs and applying self-aging approach. The red InP-QLED with optimized interfacial contact exhibits a significant improvement in maximum external quantum efficiency and current efficiency from 4.42 to 10.2% and 4.70 to 10.8 cd/A, respectively, after 69 days of self-aging, which is an almost 2.3-fold improvement compared to the fresh device. The analysis indicates the consecutive reduction in electron injection and accumulation in the emissive QD due to changes in the conduction band minimum of ZnMgO (0.1 eV after 10 days of storage) through a downward vacuum-level shift according to the aging times. During the device aging periods, the oxygen vacancy of ZnMgO reduces, which leads to lower the conductivity of ZnMgO. As a result, charge balance of the device is improved with the suppression of exciton quenching at the interface of ZnMgO and InP-QD.",

keywords = "cadmium-free quantum dots, charge balance, charge carrier injection layers, inverted structure, light-emitting diode",

author = "Lee, {Chae Young} and {Naik Mude}, Nagarjuna and Raju Lampande and Eun, {Kwan Ju} and Yeom, {Ji Eun} and Choi, {Hyung Sik} and Sohn, {Sang Hyun} and Yoo, {Jun Mo} and Kwon, {Jang Hyuk}",

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AU - Naik Mude, Nagarjuna

AU - Lampande, Raju

AU - Eun, Kwan Ju

AU - Yeom, Ji Eun

AU - Choi, Hyung Sik

AU - Sohn, Sang Hyun

AU - Yoo, Jun Mo

AU - Kwon, Jang Hyuk

PY - 2019/10/9

Y1 - 2019/10/9

N2 - Here, we report an efficient inverted red indium phosphide (InP) comprising QD (InP/ZnSe/ZnS, core/shell structure) light-emitting diode (QLED) by modulating an interfacial contact between the electron transport layer and emissive InP-QDs and applying self-aging approach. The red InP-QLED with optimized interfacial contact exhibits a significant improvement in maximum external quantum efficiency and current efficiency from 4.42 to 10.2% and 4.70 to 10.8 cd/A, respectively, after 69 days of self-aging, which is an almost 2.3-fold improvement compared to the fresh device. The analysis indicates the consecutive reduction in electron injection and accumulation in the emissive QD due to changes in the conduction band minimum of ZnMgO (0.1 eV after 10 days of storage) through a downward vacuum-level shift according to the aging times. During the device aging periods, the oxygen vacancy of ZnMgO reduces, which leads to lower the conductivity of ZnMgO. As a result, charge balance of the device is improved with the suppression of exciton quenching at the interface of ZnMgO and InP-QD.

AB - Here, we report an efficient inverted red indium phosphide (InP) comprising QD (InP/ZnSe/ZnS, core/shell structure) light-emitting diode (QLED) by modulating an interfacial contact between the electron transport layer and emissive InP-QDs and applying self-aging approach. The red InP-QLED with optimized interfacial contact exhibits a significant improvement in maximum external quantum efficiency and current efficiency from 4.42 to 10.2% and 4.70 to 10.8 cd/A, respectively, after 69 days of self-aging, which is an almost 2.3-fold improvement compared to the fresh device. The analysis indicates the consecutive reduction in electron injection and accumulation in the emissive QD due to changes in the conduction band minimum of ZnMgO (0.1 eV after 10 days of storage) through a downward vacuum-level shift according to the aging times. During the device aging periods, the oxygen vacancy of ZnMgO reduces, which leads to lower the conductivity of ZnMgO. As a result, charge balance of the device is improved with the suppression of exciton quenching at the interface of ZnMgO and InP-QD.

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Efficient Cadmium-Free Inverted Red Quantum Dot Light-Emitting Diodes

Abstract

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Keywords

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