Fig. 2: QD-alizarin complexes as a model system for charge transfer studies.
From: Marcus inverted region of charge transfer from low-dimensional semiconductor materials
a Photoexcitation of QD-surface-bound alizarin (AZ) initiates electron transfer (ET) from the lowest unoccupied molecular orbital (LUMO) of molecules to the conduction band (CB) level(s) of QDs, which is followed by charge recombination (CR-1) from the lowest CB level of QDs to the highest occupied molecular orbital (HOMO) of molecules. Alternatively, exciting the QD triggers interfacial hole transfer (HT) from the valence band (VB) of the QD to the HOMO of AZs, which is also followed by another charge recombination process (CR-2) from the CB level of QDs to the triplet LUMO of AZs. b Absorption spectra of a series of CdS QD–AZ complexes dispersed in hexane with different QD sizes. The gray shading depicts the absorption band of surface-bound AZ. Inset is a representative transmission electron microscope (TEM) image of CdS QDs.
