Excitonic Photoluminescence from Nanodisc States in Graphene Oxides
Excitonic Photoluminescence from Nanodisc States in Graphene Oxides
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DOI：
10.1021/jz500516u
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发表时间：
2014-05-15
影响因子：
5.7
通讯作者：
Matsuda, Kazunari
中科院分区：
文献类型：
--
作者：
Kozawa, Daichi;Zhu, Xi;Matsuda, Kazunari
利用光致发光（PL）激发光谱、时间分辨PL光谱和基于体微扰理论的密度泛函理论研究了氧化石墨烯（GO）近红外（NIR）发光的起源。实验观察到的近红外光致发光峰的能量依赖于激发能量，并且随着激发能量的增加，峰的宽度增加。结果发现，在时间分辨光谱中的PL衰减曲线在较低的发射能量下显示出由于嵌入在GO中的较小到较大的石墨烯纳米盘（GND）状态之间的能量转移而导致的积聚行为。我们证明了近红外光致发光起源于几个纳米大小的GND态的系综发射。理论计算揭示了不同尺寸的单个GND态的电子和激子性质，这解释了非均匀加宽的近红外PL。我们进一步证明，电子性质是高度敏感的质子化和去质子化过程的GND状态，使用实验和理论方法。
The origin of near-infrared (NIR) luminescence from graphene oxide (GO) is investigated by photoluminescence (PL) excitation spectroscopy, time-resolved PL spectroscopy, and density functional theory based many body perturbation theories. The energy of experimentally observed NIR PL peak depends on the excitation energy, and the peak broadens with increasing excitation energy. It is found that the PL decay curves in time-resolved spectroscopy show build-up behavior at lower emission energies due to energy transfer between smaller to larger graphene nanodisc (GND) states embedded in GO. We demonstrate that the NIR PL originates from ensemble emission of GND states with a few nanometers in size. The theoretical calculations reveal the electronic and excitonic properties of individual GND states with various sizes, which accounts for the inhomogeneously broadened NIR PL. We further demonstrate that the electronic properties are highly sensitive to the protonation and deprotonation processes of GND states using both the experimental and theoretical approaches.