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

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buir.contributor.authorDemir, Hilmi Volkan
buir.contributor.orcidDemir, Hilmi Volkan|0000-0003-1793-112X
dc.citation.epage486en_US
dc.citation.issueNumber2en_US
dc.citation.spage480en_US
dc.citation.volumeNumber5en_US
dc.contributor.authorShendre, S.en_US
dc.contributor.authorSharma, V. K.en_US
dc.contributor.authorDang C.en_US
dc.contributor.authorDemir, Hilmi Volkanen_US
dc.date.accessioned2019-02-21T16:02:26Z
dc.date.available2019-02-21T16:02:26Z
dc.date.issued2018en_US
dc.departmentDepartment of Electrical and Electronics Engineeringen_US
dc.departmentInstitute of Materials Science and Nanotechnology (UNAM)en_US
dc.departmentDepartment of Physicsen_US
dc.description.abstractColloidal 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.
dc.description.sponsorshipThis research is supported by the National Research Foundation, Prime Minister’s Office, Singapore, under its NRF Investigatorship Award Program (NRF-NRFI2016-08) and the Singapore Agency for Science, Technology and Research (A*STAR) SERC Pharos Program under Grant No. 152 73 00025. H.V.D. gratefully acknowledges TUBA-GEBIP, and C.D. acknowledges support from the Nanyang Technological University start-up grant M4081482.
dc.identifier.doi10.1021/acsphotonics.7b00984
dc.identifier.eissn2330-4022
dc.identifier.urihttp://hdl.handle.net/11693/50003
dc.language.isoEnglish
dc.publisherAmerican Chemical Society
dc.relation.isversionofhttps://doi.org/10.1021/acsphotonics.7b00984
dc.relation.projectNRF-NRFI2016-08 - National Research Foundation, NRF - Agency for Science, Technology and Research, A*STAR - 152 73 00025 - Nanyang Technological University, NTU: M4081482
dc.source.titleACS Photonicsen_US
dc.subjectAuger recombinationen_US
dc.subjectColloidal quantum dotsen_US
dc.subjectElectroluminescenceen_US
dc.subjectExciton dynamicsen_US
dc.subjectLight-emitting diodesen_US
dc.subjectSemiconductor nanocrystalsen_US
dc.titleExciton dynamics in colloidal quantum-dot LEDs under active device operationsen_US
dc.typeArticleen_US

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