The photophysics of colloidal quantum dots significantly affect their performance in photocatalysis and optoelectronics. Here, a combination of steady-state and time-resolved photoluminescence (SSPL and TRPL) data demonstrate that energy and charge transfer between an inorganic nanocrystal (NC) donor and organic molecular acceptor are acutely sensitive to the chemical moiety linking the two species. Here, we use the same donor CdS NCs in combination with molecular acceptors that have the same overlap integral but bind differently with the NC. Experiments show that only resonance energy transfer (RET) with a rate of 0.067 ns<sup>-1</sup> is observed for the carboxylic-acid-functionalized ligand, while a more rapid RET (0.24 ns<sup>-1</sup>) process as well as charge transfer are observed for the amine-functionalized ligand. This is seen with a series of CdS NCs of different sizes. The heterogeneity in energy transfer rates that result from these commonly used ligands provides an easy way to tune NC photophysical properties. This rapid and controllable energy transfer process can be utilized in making high efficiency solar cell or other optoelectronic devices. This study brings a more profound understanding of the NC surface chemistry.

Distinctive, selective ligand binding sites on CdS nanocrystals affecting energy and charge transfer

251st National Meeting (2016)

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