Singhal, Pallavi ; Ghosh, Hirendra N. (2015) Hot-hole extraction from quantum dot to molecular adsorbate Chemistry - A European Journal, 21 (11). pp. 4405-4412. ISSN 0947-6539
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Official URL: http://onlinelibrary.wiley.com/doi/10.1002/chem.20...
Related URL: http://dx.doi.org/10.1002/chem.201405947
Abstract
Ultrafast thermalized and hot-hole-transfer processes have been investigated in CdSe quantum dot (QD)/catechol composite systems in which hole transfer from photoexcited QDs to the catechols is thermodynamically favorable. A series of catechol derivatives were selected with different electron-donating and -withdrawing groups, and the effect of these groups on hole transfer and charge recombination (CR) dynamics has been investigated. The hole-transfer time was determined using the fluorescence upconversion technique and found to be 2–10 ps depending on the molecular structure of the catechol derivatives. The hot-hole-transfer process was followed after monitoring 2S luminescence of CdSe QDs. Interestingly, hot-hole extraction was observed only in the CdSe/3-methoxycatechol (3-OCH3) composite system owing to the higher electron-donating property of the 3-methoxy group. To confirm the extraction of the hot hole and to monitor the CR reaction in CdSe QD/catechol composite systems, ultrafast transient absorption studies have been carried out. Ultrafast transient-absorption studies show that the bleach recovery kinetics of CdSe QD at the 2S excitonic position is much faster in the presence of 3-OCH3. This faster bleach recovery at the 2S position in CdSe/3-OCH3 suggests hot-hole transfer from CdSe QD to 3-OCH3. CR dynamics in CdSe QD/catechol composite systems was followed by monitoring the excitonic bleach at the 1S position and was found to decrease with free energy of the CR reaction.
Item Type: | Article |
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Source: | Copyright of this article belongs to John Wiley and Sons, Inc. |
Keywords: | Adsorbates; Catechols; Charge Recombination; Hole Extraction; Quantum Dots |
ID Code: | 102016 |
Deposited On: | 27 Jan 2017 17:27 |
Last Modified: | 27 Jan 2017 17:27 |
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