Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Takamatsu, Kagawa 761-0395, Japan.
ACS Nano. 2012 Feb 28;6(2):1601-8. doi: 10.1021/nn204567d. Epub 2012 Jan 30.
Quantum dots-based electron donor-acceptor systems play a rising role in the design of renewable and carbon-free energy harvesting technologies. In this article, we discuss the photofabrication of fullerene-shelled quantum dots supramolecular nanoparticles, in which the fullerene shell acts as not only a well-defined electron acceptor but also a robust protecting layer against the photocorrosion of the quantum dot core. We evaluate the ensemble and single-molecule electron transfer from the core to the shell in the nanoparticles and the photocurrent response of a photoelectrochemical cell constructed using the nanoparticles. The supramolecular nanoparticle has been prepared by the covalent tethering of a fullerene-thiol monolayer to the quantum dot followed by the photochemical reactions of free fullerene-thiol to the tethered monolayer. The nanoparticles are characterized using scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Correlated single-photon emission and the two-state ON-OFF photoluminescence show that single quantum dots are included in the supramolecular nanoparticles. The fullerene-shells suppress the blinking of single quantum dots by acting as well-defined electron traps, without allowing the transfer of Auger electrons to unknown traps. Electron transfer from the quantum dot-core to the fullerene-shell is apparent from the short ON and OFF durations in the photoluminescence intensity trajectories of single quantum dots, quenching of the photoluminescence intensity and lifetime of quantum dots at the ensemble level, and the characteristic transient absorption band of the anion radical of fullerene. We next construct a photoelectrochemical cell using the supramolecular nanoparticles, and the transferred electron is externally driven in the cell to generate ∼400 μA/cm(2) photocurrent. Electron transfer from the highly stable quantum dots to the protecting fullerene-shells places the supramolecular nanoparticles among the most promising antenna systems for the construction of cost-effective and stable next generation solar energy harvesting systems.
基于量子点的给体-受体体系在可再生和无碳能源收集技术的设计中发挥着越来越重要的作用。在本文中，我们讨论了富勒烯壳层量子点超分子纳米粒子的光致加工，其中富勒烯壳不仅作为一个定义明确的电子受体，而且作为量子点核心光腐蚀的坚固保护层。我们评估了纳米粒子中核心到壳的整体和单分子电子转移以及使用纳米粒子构建的光电化学电池的光电流响应。超分子纳米粒子是通过将富勒烯-硫醇单层共价键接到量子点上，然后通过自由富勒烯-硫醇的光化学反应制备的。使用扫描电子显微镜、原子力显微镜和 X 射线光电子能谱对纳米粒子进行了表征。相关单光子发射和双态 ON-OFF 光致发光表明，单个量子点包含在超分子纳米粒子中。富勒烯壳通过作为定义明确的电子陷阱抑制单个量子点的闪烁，而不允许俄歇电子转移到未知陷阱。从单个量子点的光致发光强度轨迹中的短 ON 和 OFF 持续时间、量子点的光致发光强度和寿命的猝灭以及富勒烯阴离子自由基的特征瞬态吸收带可以明显看出电子从量子点核心转移到富勒烯壳。我们接下来使用超分子纳米粒子构建了一个光电化学电池，并在外电路中驱动转移电子以在电池中产生约 400 μA/cm(2)的光电流。从高度稳定的量子点到保护富勒烯壳的电子转移使超分子纳米粒子成为构建具有成本效益和稳定的下一代太阳能收集系统的最有前途的天线系统之一。
