Quantitative Modeling of Electron Dynamics and the Effect of Diffusion in Photosensitized Semiconductor Nanocomposites
| Autor: | Hui Fang, Michael J. Wilhelm, Jianqiang Ma, Danielle L. Kuhn, Zachary Zander, Hai-Lung Dai |
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| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Accounts of Chemical Research. 55:1879-1888 |
| ISSN: | 1520-4898 0001-4842 |
| DOI: | 10.1021/acs.accounts.2c00073 |
| Popis: | Photosensitized semiconducting nanomaterials have received considerable attention because of their applications in photocatalytic and photoelectronic devices. In such systems, photoexcited electrons with sufficiently high energies can be injected into the conduction band (CB) of an adjacent semiconductor. These excited electrons are subjected to various physical processes that can lead to their annihilation before exercising their catalytic/electric functions, and the efficiency of the photosensitized functions depends on the quantity of CB electrons produced and how long they remain near the surface region of the semiconductor. The rise and decay of photoexcited electrons in the semiconductor CB can be probed with transient IR absorption (TA), which was first demonstrated by Lian and co-workers. Results from various laboratories have since revealed that electrons appear in the CB following the excitation of the photosensitizer in tens to hundreds of femtoseconds and that the decay of the CB electrons typically exhibits multiple exponentials on varying ultrafast time scales. The size of the semiconductor nanoparticle appears to influence the diffusion of the CB electrons and thus their lifetimes. In all studies reported, the observed multiexponential decays have been analyzed and interpreted using purely phenomenological models, in which the individual decays were intuitively assigned to one specific relaxation or loss process. In reality, however, each exponential decay can be a convolution of multiple physical processes. In this Account, we report a universally applicable physical model, constructed by including all known electron dynamic processes, to quantitatively account for the multiexponential decays. We characterize the model as universal, as it can be used to analyze our own TA measurements, as well as data acquired in other laboratories. In our study of TiO |
| Databáze: | OpenAIRE |
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