Photoinduced Electron Transfer Between Pyridine Coated Cadmium Selenide Quantum Dots and Single Sheet Graphene
Photoinduced Electron Transfer Between Pyridine Coated Cadmium Selenide Quantum Dots and Single Sheet Graphene
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DOI：
10.1002/adfm.201203652
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发表时间：
2013-11-06
影响因子：
19
通讯作者：
Ozkan, Mihrimah
中科院分区：
文献类型：
--
作者：
Guo, Shirui;Bao, Duoduo;Ozkan, Mihrimah
在过去的几年里，石墨烯作为能源应用和纳米电子学的二维量子阱材料的兴趣呈指数级增长。大面积单片制造原始石墨烯的最新进展为从纳米级扩展到中尺度应用开辟了未探索的途径。单层石墨烯相对较低的吸收率和激子的短寿命表明，它需要与光敏剂结合，以探索其在光子应用（如太阳能转换）中的可行性。红光发射的CdSe量子点用于光敏化具有几平方厘米面积的单层石墨烯。量子点的吡啶涂层不仅增强了它们对石墨烯表面的粘附力，而且还提供了CdSe和二维碳同素异形体之间的良好的电子耦合。量子点的照明导致在石墨烯相中注入n-载流子。时间分辨光谱揭示了三种模式的光诱导电子转移之间的量子点和石墨烯发生在飞秒和皮秒时域。瞬态吸收光谱提供了证据的光致空穴位移的CdSe的吡啶配体，从而极化的量子点的表面。也就是说，光致电极化，其有利于同时从CdSe到石墨烯相的电子转移。这些光诱导界面电荷转移的机理见解具有很大的潜力，可以作为设计和开发石墨烯和无机纳米材料复合材料用于太阳能转换应用的指南。
Interest in graphene as a two-dimensional quantum-well material for energy applications and nanoelectronics has increased exponentially in the last few years. The recent advances in large-area single-sheet fabrication of pristine graphene have opened unexplored avenues for expanding from nano- to meso-scale applications. The relatively low level of absorptivity and the short lifetimes of excitons of single-sheet graphene suggest that it needs to be coupled with light sensitizers in order to explore its feasibility for photonic applications, such as solar-energy conversion. Red-emitting CdSe quantum dots are employed for photosensitizing single-sheet graphene with areas of several square centimeters. Pyridine coating of the quantum dots not only enhances their adhesion to the graphene surface, but also provides good electronic coupling between the CdSe and the two-dimensional carbon allotrope. Illumination of the quantum dots led to injection of n-carrier in the graphene phase. Time-resolved spectroscopy reveals three modes of photoinduced electron transfer between the quantum dots and the graphene occurring in the femtosecond and picosecond time-domains. Transient absorption spectra provide evidence for photoinduced hole-shift from the CdSe to the pyridine ligands, thereby polarizing the surface of the quantum dots. That is, photoinduced electrical polarization, which favors the simultaneous electron transfer from the CdSe to the graphene phase. These mechanistic insights into the photoinduced interfacial charge transfer have a promising potential to serve as guidelines for the design and development of composites of graphene and inorganic nanomaterials for solar-energy conversion applications.