F�rster resonance energy transfer (FRET) has been employed to improve the spectral range of light harvesting in photovoltaic devices through the use of semiconductor nanomaterials acting as energy transfer donors to various organic dyes. One such previously employed nanomaterial-dye pair, CdSe quantum dots (QDs) coupled with a squaraine dye possessing a thiol functional group (SQSH), was investigated to better understand the potential of utilizing energy transfer processes in solar cells. Steady state and time resolved spectroscopy experiments were carried out using various sizes of CdSe QDs to examine how changes in QD size dependent properties affected the energy transfer processes occurring in the system. Photoluminescence studies revealed that smaller QDs have higher energy transfer efficiencies than larger QDs despite the higher spectral overlap of the latter. Ultrafast transient absorption experiments showed that the higher efficiency observed in smaller sizes of QDs was an additional energy transfer process occurring through a Dexter Energy Transfer (DET) mechanism due to increasing wavefunction overlap with decreasing size. This electron exchange interaction represents a new way to utilize energy transfer to maximize the light harvesting capabilities of photovoltaic devices.

CdSe quantum dot-squaraine light harvesting assemblies: Size dependent energy transfer mechanisms

248th National Meeting (2014)

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