Sharma, Shailesh N. and Vats, Tanvi and Dhenadhayalan, N. and Ramamurthy, P. and Narula, A. K. (2012) Ligand-dependent transient absorption studies of hybrid polymer:CdSe quantum dot composites. Solar Energy Materials and Solar Cells , 100. pp. 6-15. ISSN 0927-0248

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Abstract

In this work, fourier transform infra-red (FTIR), photoluminescence (PL), optical and transient absorption (UV-vis & TA) spectroscopies have been used to monitor charge transfer from excited conjugated polymer (MEH-PPV) to smaller sized (5-7 nm) monodispersive CdSe quantum dots (QD) prepared by the chemical route using different capping ligands as trioctyl phosphine oxide (TOPO) and oleic acid (OA). CdSe (OA) QD's (similar to 7 nm) owing to its relatively smaller surface energies compared with CdSe (TOPO) QD's (similar to 5 nm) shows lesser quenching capabilities within the MEH-PPV polymer matrix. These studies demonstrate dominance of respective processes of photoinduced Forster energy transfer between host polymer (donors) and guest CdSe nanocrystals (acceptors) in polymer:CdSe(OA) nanocomposites and charge transfer in polymer:CdSe(TOPO) nanocomposites. Due to limitations of our nanosecond laser flash photolysis apparatus, transient absorption signatures of positive polaron of MEH-PPV could not be detected since it exhibits characteristic absorption in the mid-IR region. However, signatures of transient corresponding to CdSe-* radical in the visible region was seen only when the sample was excited in the presence of polymer (MEH-PPV). A model has been proposed, which elucidate the possibility to modulate charge/energy transfer rate between polymer and semiconductor quantum dots using a suitable ligand-exchange process. The various characterization techniques used in this work provide an insight into the charge separation, charge accumulation and/or trapping of charge carriers for the better understanding of hybrid organic-inorganic photovoltaics.

Item Type:	Article
Additional Information:	Copyright for this article belongs to M/s Elsevier.
Subjects:	Energy Fuels Materials Science Applied Physics/Condensed Matter
Divisions:	UNSPECIFIED
Depositing User:	Users 27 not found.
Date Deposited:	13 Mar 2020 11:23
Last Modified:	13 Mar 2020 11:23
URI:	http://npl.csircentral.net/id/eprint/3513

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