Exciton dynamics in colloidal quantum-dot leds under active device operations

Colloidal quantum-dot light-emitting diodes (QLEDs) are lucrative options for color-pure lighting sources. To achieve high-performance QLEDs, besides developing high-efficiency quantum dots (QDs), it is essential to understand their device physics. However, little understanding of the QD emission be...

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Main Authors: Shendre, Sushant, Sharma, Vijay Kumar, Dang, Cuong, Demir, Hilmi Volkan
Other Authors: School of Electrical and Electronic Engineering
Format: Article
Language:English
Published: 2019
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Online Access:https://hdl.handle.net/10356/88950
http://hdl.handle.net/10220/48349
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-889502023-02-28T19:31:57Z Exciton dynamics in colloidal quantum-dot leds under active device operations Shendre, Sushant Sharma, Vijay Kumar Dang, Cuong Demir, Hilmi Volkan School of Electrical and Electronic Engineering School of Physical and Mathematical Sciences Centre of Excellence for Semiconductor Lighting and Displays The Photonics Institute Exciton Dynamics Electroluminescence DRNTU::Engineering::Electrical and electronic engineering Colloidal quantum-dot light-emitting diodes (QLEDs) are lucrative options for color-pure lighting sources. To achieve high-performance QLEDs, besides developing high-efficiency quantum dots (QDs), it is essential to understand their device physics. However, little understanding of the QD emission behavior in active QLEDs is one of the main factors hindering the improvement of device efficiency. In this work, we systematically studied the exciton dynamics of gradient composition CdSe@ZnS QDs during electroluminescence in a working QLED. With time-resolved photoluminescence analyses using fluorescence lifetime imaging microscopy we analyzed a large population of QDs spatially spreading over an extended area inside and outside the device. This allows us to reveal the statistically significant changes in the behavior of QD emission in the device at different levels of applied voltages and injection currents. We find that the QD emission efficiency first drops in device fabrication with Al electrode deposition and that the QD exciton lifetime is then statistically reduced further under the QLED’s working conditions. This implies the nonradiative Auger recombination process is active in charged QDs as a result of imbalanced charge injection in a working QLED. Our results help to understand the exciton behavior during the operation of a QLED and demonstrate a new approach to explore the exciton dynamics statistically with a large QD population. NRF (Natl Research Foundation, S’pore) ASTAR (Agency for Sci., Tech. and Research, S’pore) Accepted version 2019-05-24T01:31:13Z 2019-12-06T17:14:25Z 2019-05-24T01:31:13Z 2019-12-06T17:14:25Z 2018 Journal Article Shendre, S., Sharma, V. K., Dang, C., & Demir, H. V. (2017). Exciton Dynamics in Colloidal Quantum-Dot LEDs under Active Device Operations. ACS Photonics, 5(2), 480-486. doi:10.1021/acsphotonics.7b00984 https://hdl.handle.net/10356/88950 http://hdl.handle.net/10220/48349 10.1021/acsphotonics.7b00984 en ACS Photonics © 2017 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Photonics, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acsphotonics.7b00984. 22 p. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Exciton Dynamics
Electroluminescence
DRNTU::Engineering::Electrical and electronic engineering
spellingShingle Exciton Dynamics
Electroluminescence
DRNTU::Engineering::Electrical and electronic engineering
Shendre, Sushant
Sharma, Vijay Kumar
Dang, Cuong
Demir, Hilmi Volkan
Exciton dynamics in colloidal quantum-dot leds under active device operations
description Colloidal quantum-dot light-emitting diodes (QLEDs) are lucrative options for color-pure lighting sources. To achieve high-performance QLEDs, besides developing high-efficiency quantum dots (QDs), it is essential to understand their device physics. However, little understanding of the QD emission behavior in active QLEDs is one of the main factors hindering the improvement of device efficiency. In this work, we systematically studied the exciton dynamics of gradient composition CdSe@ZnS QDs during electroluminescence in a working QLED. With time-resolved photoluminescence analyses using fluorescence lifetime imaging microscopy we analyzed a large population of QDs spatially spreading over an extended area inside and outside the device. This allows us to reveal the statistically significant changes in the behavior of QD emission in the device at different levels of applied voltages and injection currents. We find that the QD emission efficiency first drops in device fabrication with Al electrode deposition and that the QD exciton lifetime is then statistically reduced further under the QLED’s working conditions. This implies the nonradiative Auger recombination process is active in charged QDs as a result of imbalanced charge injection in a working QLED. Our results help to understand the exciton behavior during the operation of a QLED and demonstrate a new approach to explore the exciton dynamics statistically with a large QD population.
author2 School of Electrical and Electronic Engineering
author_facet School of Electrical and Electronic Engineering
Shendre, Sushant
Sharma, Vijay Kumar
Dang, Cuong
Demir, Hilmi Volkan
format Article
author Shendre, Sushant
Sharma, Vijay Kumar
Dang, Cuong
Demir, Hilmi Volkan
author_sort Shendre, Sushant
title Exciton dynamics in colloidal quantum-dot leds under active device operations
title_short Exciton dynamics in colloidal quantum-dot leds under active device operations
title_full Exciton dynamics in colloidal quantum-dot leds under active device operations
title_fullStr Exciton dynamics in colloidal quantum-dot leds under active device operations
title_full_unstemmed Exciton dynamics in colloidal quantum-dot leds under active device operations
title_sort exciton dynamics in colloidal quantum-dot leds under active device operations
publishDate 2019
url https://hdl.handle.net/10356/88950
http://hdl.handle.net/10220/48349
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