AVS 59th Annual International Symposium and Exhibition
    Energy Frontiers Focus Topic Thursday Sessions
       Session EN-ThP

Paper EN-ThP10
Investigation of the Molecular Interaction between CdSe Quantum Dots and P3HT for Hybrid Solar Cell Applications

Thursday, November 1, 2012, 6:00 pm, Room Central Hall

Session: Energy Frontiers Poster Session
Presenter: S. Thevuthasan, Pacific Northwest National Laboratory
Authors: A.S. Karakoti, Pacific Northwest National Laboratory
P. Nachimuthu, Pacific Northwest National Laboratory
S. Thevuthasan, Pacific Northwest National Laboratory
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We took a systematic approach to study the interaction between CdSe quantum dots (QDs) and regioregular P3HT polymer using spectroscopic and imaging tools. Photoluminescence (PL) measurements following the titration of CdSe quantum dots with P3HT showed evidence of charge transfer between the CdSe QDs and the P3HT matrix. The titration led to an immediate quenching of main PL emission from both CdSe and P3HT and a new emission in low energy region of the electromagnetic spectrum starts appearing from the recombination of electrons in CdSe with holes in P3HT. The effect of the size of QDs on charge transfer as a function of reaction time following the addition of CdSe quantum dots in to a fixed concentration of P3HT was monitored. The time course PL measurements show the quenching of main PL emission from P3HT follow the order 6.6 nm<3.3 nm<2.1 nm while no significant changes was observed in the absorbance spectrum. These results suggest that the size-dependent interaction between QDs and P3HT. However, dynamic light scattering measurements (DLS) from the ligand capped CdSe QDs indicate a strong tendency for agglomeration of smaller QDs in the presence of P3HT. Addition of P3HT to a known concentration of CdSe QDs increases their average diameter for 2.1nm and 3.3nm QDs in toluene while the average diameter of QDs with 6.6nm in toluene remains unchanged at the same concentrations. This suggests that the interaction between CdSe QDs and P3HT is controlled by the agglomeration of QDs and not by the size of the dots. Findings from these results and the effect of changing the capping ligands of CdSe QDs on the charge transfer will be discussed.