Anomalous Behaviors of Visible Luminescence from Graphene Quantum Dots: Interplay between Size and Shape

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• 作者：Sung Kim ; Sung Won Hwang ; Min-Kook Kim ; Dong Yeol Shin ; Dong Hee Shin ; Chang Oh Kim ; Seung Bum Yang ; Jae Hee Park ; Euyheon Hwang ; Suk-Ho Choi ; Geunwoo Ko ; Sunghyun Sim ; Cheolsoo Sone ; Hyoung Joon Choi ; Sukang Bae ; Byung Hee Hong
• 刊名：ACS Nano
• 出版年：2012
• 出版时间：September 25, 2012
• 年：2012
• 卷：6
• 期：9
• 页码：8203-8208
• 全文大小：444K
• 年卷期：v.6,no.9(September 25, 2012)
• ISSN：1936-086X

文摘

For the application of graphene quantum dots (GQDs) to optoelectronic nanodevices, it is of critical importance to understand the mechanisms which result in novel phenomena of their light absorption/emission. Here, we present size-dependent shape/edge-state variations of GQDs and visible photoluminescence (PL) showing anomalous size dependences. With varying the average size (d_a) of GQDs from 5 to 35 nm, the peak energy of the absorption spectra monotonically decreases, while that of the visible PL spectra unusually shows nonmonotonic behaviors having a minimum at d_a = 17 nm. The PL behaviors can be attributed to the novel feature of GQDs, that is, the circular-to-polygonal-shape and corresponding edge-state variations of GQDs at d_a = 17 nm as the GQD size increases, as demonstrated by high-resolution transmission electron microscopy.

Keywords:

graphene; quantum dot; size; shape; edge; photoluminescence