title: Origin of White Electroluminescence in Graphene Quantum Dots Embedded Host/Guest Polymer Light Emitting Diodes.
abstract: Polymer light emitting diodes (PLEDs) using quantum dots (QDs) as emissive materials have received much attention as promising components for next-generation displays. Despite their outstanding properties, toxic and hazardous nature of QDs is a serious impediment to their use in future eco-friendly opto-electronic device applications. Owing to the desires to develop new types of nano-material without health and environmental effects but with strong opto-electrical properties similar to QDs, graphene quantum dots (GQDs) have attracted great interest as promising luminophores. However, the origin of electroluminescence from GQDs incorporated PLEDs is unclear. Herein, we synthesized graphene oxide quantum dots (GOQDs) using a modified hydrothermal deoxidization method and characterized the PLED performance using GOQDs blended poly(N-vinyl carbazole) (PVK) as emissive layer. Simple device structure was used to reveal the origin of EL by excluding the contribution of and contamination from other layers. The energy transfer and interaction between the PVK host and GOQDs guest were investigated using steady-state PL, time-correlated single photon counting (TCSPC) and density functional theory (DFT) calculations. Experiments revealed that white EL emission from the PLED originated from the hybridized GOQD-PVK complex emission with the contributions from the individual GOQDs and PVK emissions.
authors.affiliation: 1] SKKU Advanced Institute of Nanotechnology (SAINT) and School of Chemical Engineering and The Institute of Science and Technology, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon 440-746, Republic of Korea [2] Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Republic of Korea.
authors.forename: Jung
authors.initials: J
authors.lastname: Kyu Kim
authors.affiliation: Institute of Advanced Composite materials, Korea Institute of Science and Technology, San 101, Eunha-ri, Bongdong-eup, Wanju-gun, Jeollabuk-do, 565-905, Republic of Korea.
authors.forename: Sukang
authors.initials: S
authors.lastname: Bae
authors.affiliation: Department of Physics, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Republic of Korea.
authors.forename: Yeonjin
authors.initials: Y
authors.lastname: Yi
authors.affiliation: Department of Chemistry, Seoul University, Seoul 151-747, Republic of Korea.
authors.forename: Myung
authors.initials: M
authors.lastname: Jin Park
authors.affiliation: Department of Chemistry, Seoul University, Seoul 151-747, Republic of Korea.
authors.forename: Sang
authors.initials: S
authors.lastname: Jin Kim
authors.affiliation: Advanced Photonics Research Institute (APRI), Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Republic of Korea.
authors.forename: NoSoung
authors.initials: N
authors.lastname: Myoung
authors.affiliation: Advanced Photonics Research Institute (APRI), Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Republic of Korea.
authors.forename: Chang-Lyoul
authors.initials: CL
authors.lastname: Lee
authors.affiliation: Department of Chemistry, Seoul University, Seoul 151-747, Republic of Korea.
authors.forename: Byung
authors.initials: B
authors.lastname: Hee Hong
authors.affiliation: Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Republic of Korea.
authors.forename: Jong
authors.initials: J
authors.lastname: Hyeok Park