세미나안내

[2015 06 26] 특별세미나 Dr. Chang-Lyoul Lee (APRI, GIST)

Light emitting diodes using eco-friendly graphene oxide quantum dots and InxGa1-xN colloidal quantum dots

MSE Graduate Students and Researchers

관리자 | 2015.06.23 17:29 | 조회 3205


신소재공학과 특별세미나

신소재공학과에서 특별 세미나를 아래와 같이 개최하오니 대학구성원 여러분들의 많은 참여 바랍니다.

 

일시: 2015 06 26 () 10:30 ~ 12:30

장소: 공학1동 202호 멀티미디어 강의실

세미나 주제: Light emitting diodes using eco-friendly graphene oxide quantum dots and InxGa1-xN colloidal quantum dots

초청연사: 이창렬 박사 (APRI, GIST)

Host of a Seminar: 이태우 교수

 

Date: JUNE 26, 2015 (FRI) 10:30 ~ 12:30

Place: Sience Builing 1, #202

Title: Light emitting diodes using eco-friendly graphene oxide quantum dots and InxGa1-xN colloidal quantum dots

Speaker: Dr. Chang-Lyoul Lee (APRI, GIST)

Host of a Seminar: Prof. Tae-Woo Lee

Abstract:

In this talk, I will introduce two topics. One is the origin of white electroluminescence in graphene quantum dots embedded host/guest polymer light emitting diodes and the other is the facile synthesis of eco-friendly InxGa1-xN colloidal quantum dots and their application to quantum dot light emitting diodes.

 

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 nanomaterial 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. (Sci Rep., 5, 11032, 2015).

 

We report the synthesis of emissive InxGa1-xN colloidal quantum dots (CQDs) using the hot-injection method and demonstrate the QD-light emitting diodes (QLEDs) using these CQDs for the first time. The band gaps of the InxGa1-xN CQDs were varied by varying the metal fraction and by particle size control. The X-ray absorption fine structure (XAFS) results show that the crystal states of the InxGa1-xN CQDs consist of multi-phase states; multi-peak (photoluminescence) PL resulted from these multi-phase states. Inverted structured QLED shows green EL emission and a maximum luminance of ~45 cd/m2. This result shows that InxGa1-xN CQDs can be a good substitute for conventional cadmium-containing CQDs in various opto-electronic applications, e.g., eco-friendly displays. (Un-published results).



Dept. of MSE / BK21+




204개(4/11페이지)
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