Energy and electron transfer interactions in semiconductor-molecular hybrids are dictated by aspects of both the nanocrystal donor and the chromophoric acceptor molecules. For the donor, nanocrystal composition can modulate spectral overlap, the surface ligand environment can influence acceptor binding and electron transfer efficiency, and the nanocrystal size can allow for greater wavefunction overlap. Hence, while interfacing nanocrystals with molecular species it is important to consider the nature of interactions while elucidating each potential pathway for excited state interactions. We have now we probed the effect of acceptor pendant group functionalization on the excited state properties in CsPbBr3–Acceptor complexes. Despite both singlet and triplet energy transfer being thermodynamically favorable, only singlet energy transfer is found to occur between the donor CsPbBr3 nanocrystals and the acceptor molecules. The pendant groups decorating the acceptor molecules are found to directly influence the singlet energy transfer process by modulating the chromophore’s binding, degree of aggregation, and the rate constant of energy transfer (kEnT), with a greater degree of functionalization leading to stronger excited state interactions. The spectroscopic analyses presented here provide important insights into tuning the interactions between nanocrystals and molecules for light harvesting and highlight the complexity of excited state energy and charge transfer processes.

Excited state interactions dictating energy flow in semiconductor nanocrystal-molecular assemblies

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