Study of ultrafast carrier dynamics of nanostructured TiO₂ films with and without CdSe quantum dot deposition using lens-free heterodyne detection transient grating technique

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• 作者：Qing Shen ; Kenji Katayama ; Masahiro Yamaguchi ; Tsuguo Sawada and Taro Toyoda
• 关键词：Titanium oxide ; Cadmium selenide ; Quantum dot ; Carrier dynamics
• 刊名：Thin Solid Films
• 出版年：2005
• 期刊代码：78_00406090
• 类别：ph
• 出版时间：2005
• 卷：486
• 期：1-2
• 页码：15-19
• 文件大小：239 K

摘要

Ultrafast carrier dynamics of nanostructured TiO₂ films with and without CdSe quantum dot (QD) deposition were studied using a lens-free heterodyne detection transient grating (LF-HD-TG) technique. The nanostructured TiO₂ films were prepared with anatase TiO₂ nanoparticles with an average diameter of 27 nm. CdSe quantum dots with an average size of 5 nm were adsorbed onto the TiO₂ films by a chemical deposition (CD) technique. The relaxation processes of the photoexcited electrons and holes can be detected separately using the LF-HD-TG technique. For the TiO₂ film without CdSe deposition, it was found that the photoexcited holes relaxed within 2 ps. For the CdSe QD deposited nanostructured TiO₂ film, two decay processes with time constants of 2 ps (τ₁) and 16 ps (τ₂) were detected. The fast decay process was attributed to photoexcited hole relaxation due to trapping in CdSe QDs. The slow decay process mainly reflected photoexcited electron transfer from CdSe QDs to TiO₂.