Photoinduced Electron Transfer Between Pyridine Coated Cadmium Selenide Quantum Dots and Single Sheet Graphene |
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Authors: | Shirui Guo Duoduo Bao Srigokul Upadhyayula Wei Wang Ali B Guvenc Jennifer R Kyle Hamed Hosseinibay Krassimir N Bozhilov Valentine I Vullev Cengiz S Ozkan Mihrimah Ozkan |
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Affiliation: | 1. Department of Electrical Engineering, Department of Chemistry, University of California, Riverside, CA 92521 USA;2. Department of Bioengineering, Department of Chemistry, Department of Biochemistry, Center for Bioengineering Research, Materials Science and Engineering Program, University of California, Riverside, CA 92521, USA;3. Materials Science and Engineering Program, Department of Mechanical Engineering, University of California, Riverside, CA 92521 USA;4. Department of Earth Sciences and Central Facility for Advanced, Microscopy and Microanalysis, University of California, Riverside, CA 92521, USA |
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Abstract: | 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. |
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Keywords: | Quantum dot CVD graphene pump‐probe femtosecond spectroscopy charge transfer field‐effect transistors |
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