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Title: Exciton dynamics in colloidal quantum-dot leds under active device operations
Authors: Shendre, Sushant
Sharma, Vijay Kumar
Dang, Cuong
Demir, Hilmi Volkan
Keywords: Exciton Dynamics
DRNTU::Engineering::Electrical and electronic engineering
Issue Date: 2018
Source: 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
Series/Report no.: ACS Photonics
Abstract: 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.
DOI: 10.1021/acsphotonics.7b00984
Schools: School of Electrical and Electronic Engineering 
School of Physical and Mathematical Sciences 
Organisations: Centre of Excellence for Semiconductor Lighting and Displays
The Photonics Institute
Rights: © 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
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:EEE Journal Articles
SPMS Journal Articles

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