Optical absorption and ultrafast carrier dynamics characterization of CdSe quantum dots deposited on different morphologies of nanostructured TiO2 films
✍ Scribed by Lina J. Diguna; Qing Shen; Akira Sato; Kenji Katayama; Tsuguo Sawada; Taro Toyoda
- Publisher
- Elsevier Science
- Year
- 2007
- Tongue
- English
- Weight
- 549 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0928-4931
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✦ Synopsis
In this study, CdSe QDs were chemically adsorbed onto the inverse opal TiO 2 film as well as the common nanocrystalline TiO 2 film. The optical absorption studied by using photoacoustic (PA) spectroscopy implies the growing and larger amount of CdSe QDs onto inverse opal TiO 2 by increasing deposition time. For the same deposition time, the growth of CdSe QD size are independent on TiO 2 matrixes, but largely deposited on the common nanocrystalline TiO 2 film than the inverse opal TiO 2 . Ultrafast carrier dynamics shows a fast (hole) decay process and a slow (electron) decay process with lifetimes of a few ps and a few tens to hundreds ps, respectively. With increasing deposition time, regarding larger size and amount of CdSe QDs, the time constant of these two processes become longer for CdSe deposited inverse opal TiO 2 samples. However, for the same deposition time, CdSe deposited inverse opal TiO 2 have the shorter lifetime of both hole and electron decay processes compared to one on nanocrystalline TiO 2 , showing that the amount of CdSe QDs, the interfaces between CdSe QDs, play important role in carrier relaxation.