Effect of Adsorption Structure upon Directional Charge Transfer and Electronic Coupling in a Hybrid Dye Sensitizer based on a Cadmium Sulfide Quantum Dot

Abstract

Dye‐functionalized quantum dots (QDs) show promise for solar photovoltaic and photocatalytic applications. However, the energy conversion efficiencies are very sensitive to the chemical environment at the QD–dye interface, which is dependent upon how the QDs and dye interact. Herein, the effect of different surface orientations for an N749 dye attached to a CdS QD upon QD–dye interactions is investigated. The results reveal that the electronic couplings for binding configurations that involve isothiocyanate anchors are generally larger than those involving carboxylate anchors. Furthermore, for some binding modes, the electronic couplings for hole transfer are comparable to those for electron transfer, implying efficient charge separation at the QD–dye interface and reduced electron–hole recombination within the QD. It is also found that the most stable adsorption geometries for the dye are those with double carboxylate anchors, which exhibit weaker electronic coupling than isothiocyanate anchors and provide favorable energy alignment for hole transfer. Overall, the current computational study reveals some fundamental aspects concerning the relationship between interfacial charge transfer for QD/dye composites and their morphologies, such as the binding geometry of the dye, interfacial energetics and donor–acceptor interactions, which benefits the design of QD‐based nanomaterials for photovoltaic and photocatalytic applications.