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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Enhanced Charge Transport and Excited-State Charge-Transfer Dynamics in a Colloidal Mixture of CdTe and Graphene Quantum Dots
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Enhanced Charge Transport and Excited-State Charge-Transfer Dynamics in a Colloidal Mixture of CdTe and Graphene Quantum Dots

机译：增强CdTe和石墨烯量子点的胶体混合物中的增强电荷传输和激发状态电荷转移动态

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摘要

Semiconductor quantum dot (QD)-graphene composites are promising materials for photovoltaics and photocatalysis because of efficient charge extraction and transport property of graphene. Analysis of their ultrafast carrier-transfer dynamics has been limited to only QD-graphene sheets, such as CdTe-graphene sheets and CdS-graphene sheets. Herein, we investigate the carrier-transfer dynamics of CdTe QDs (CdTe QDs) in the presence and absence of graphene QsDs by using femtosecond transient absorption spectroscopy. Although the surfaces of both the QDs are in negatively charged state, as evident from the zeta potential measurements, we observed a strong excited-state interaction between two similarly charged QDs, leading to an efficient quenching of the excitonic emission of the CdTe QDs in the presence of GQDs. A detailed analysis of the rise time and 1S bleach recovery provides the evidence of electron transfer from CdTe QDs to GQDs with the hole-trapping process by surface defects. On the basis of the mechanistic study, an overall charge-transfer scheme that accounts for the faster bleach recovery of CdTe QDs in the presence of GQDs is proposed. Moreover, we have evidenced the consequences of charge transfer through the measurements of improved four-probe photoconductivity (from 1.39 (+/- 0.12) x 10(-4) S m(-1) to 1.47 (+/- 0.24) x 10(-3) S m(-1)) and decreased charge-transfer resistance [from 6944 (+/- 0.3) to 5761 (+/- 0.3) Omega] exhibited by CdTe QDs in the presence of GQDs. These findings described in the present study are hoped to open up design strategies for developing light-harvesting inorganic- organic hybrid QD assemblies with better efficiency.
机译：半导体量子点（QD）型图形复合材料是光伏和光催化的有希望的材料，因为石墨烯的有效电荷提取和运输性能。其超快载体转移动力学的分析仅限于QD-石墨烯片，例如CdTe-石墨烯片和Cds-石墨烯片。在此，我们通过使用飞秒瞬态吸收光谱检查石墨烯QSD的存在和不存在CdTe QDS（CDTE QDS）的载体转移动态。尽管QD的表面具有带负电的状态，但从Zeta电位测量中明显看出，我们观察到两个类似电荷的QD之间的强烈兴奋状态相互作用，从而有效地淬火的CDTE QD的激发率发射GQDS的存在。对上升时间和1S漂白恢复的详细分析提供了通过表面缺陷的空穴捕获过程从CDTE QDS从CDTE QDS转移到GQD的证据。在机械研究的基础上，提出了一种整体电荷转移方案，其在GQDS存在下考虑CDTE QDS更快的漂白素恢复。此外，我们已经证明了通过改善的四探针光电导性的测量（从1.39（+/- 0.12）×10（-4）S m（-1）至1.47（+/- 0.24）×10的测量（-3）S m（-1）），在GQDS存在下，CDTE QDS在GQDS存在下，降低电荷转移阻力[来自6944（+/- 0.3）至5761（+/- 0.3）ω]。希望本研究中描述的这些发现能够开辟开发光收获无机 - 有机混合QD组件的设计策略，具有更好的效率。

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