Daegu Center , Korea Basic Science Institute , Daegu 41566 , Republic of Korea.
Surface Technology Division Korea Institute of Materials Science , Changwon , Gyeongnam 51508 , Republic of Korea.
ACS Appl Mater Interfaces. 2018 Apr 25;10(16):14079-14086. doi: 10.1021/acsami.7b19524. Epub 2018 Apr 16.
Here, we study the plasmonic metal-enhanced fluorescence properties of blue-emitting graphene quantum dots (GQDs) and green-emitting graphene oxide quantum dots (GOQDs) using fluorescence lifetime imaging microscopy. Reactive ion sputtered silver (Ag) on zinc oxide (ZnO) thin films deposited on silicon (Si) wafers are used as the substrates. The morphology of the sputtered Ag gradually changes from nanoislands, via and elongated network and a continuous film with nanoholes, to a continuous film with increasing sputtering time. The fluorescence properties of GQD and GOQD on the Ag are modulated in terms of the intensities and lifetimes as the morphology of the Ag layers changes. Although both GQD and GOQD show similar fluorescence modulation on the Ag nanofilms, the fluorescence of GQD is enhanced, whereas that of GOQD is quenched due to the charge transfer process from GOQD to ZnO. Moreover, the GQD and GOQD exhibit different fluorescence lifetimes due to the effect of their electronic configurations. The theoretical calculation explains that the fluorescence amplification on the Ag nanofilms can largely be attributed to the enhanced absorption mechanism arising from accumulated optical fields around nanogaps and nanovoids in the Ag nanofilms.
在这里，我们使用荧光寿命成像显微镜研究了蓝色发射的石墨烯量子点（GQDs）和绿色发射的氧化石墨烯量子点（GOQDs）的等离子体金属增强荧光特性。使用反应离子溅射在沉积在硅（Si）晶片上的氧化锌（ZnO）薄膜上溅射银（Ag）作为衬底。溅射 Ag 的形态逐渐从纳米岛、拉长的网络和带有纳米孔的连续薄膜，到具有越来越多纳米孔的连续薄膜，随着溅射时间的增加而变化。随着 Ag 层形态的变化，GQD 和 GOQD 在 Ag 上的荧光性质在强度和寿命方面发生了调制。尽管 GQD 和 GOQD 在 Ag 纳米薄膜上表现出相似的荧光调制，但由于从 GOQD 到 ZnO 的电荷转移过程，GQD 的荧光增强，而 GOQD 的荧光猝灭。此外，由于其电子结构的影响，GQD 和 GOQD 表现出不同的荧光寿命。理论计算表明，Ag 纳米薄膜上的荧光放大主要归因于 Ag 纳米薄膜中纳米间隙和纳米空隙周围累积光学场引起的增强吸收机制。
