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

作者：Kim, Sung; Hwang, Sung Won; Kim, Min-Kook; Shin, Dong Yeol; Shin, Dong Hee; Kim, Chang Oh; Yang, Seung Bum; Park, Jae Hee; Hwang, Euyheon; Choi, Suk-Ho^*; Ko, Geunwoo; Sim, Sunghyun; Sone, Cheolsoo; Choi, Hyoung Joon; Bae, Sukang; Hong, Byung Hee

来源：ACS Nano, 2012, 6(9): 8203-8208.

DOI：10.1021/nn302878r

• graphene
• quantum dot
• size
• shape
• edge
• photoluminescence

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) = similar to 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) = similar to 17 nm as the GQD size increases, as demonstrated by high-resolution transmission electron microscopy.

• 出版日期2012-9