Tunability of Size, B Doping and Organic Molecular Coupling to Electronic and Optical Properties of Silicon Quantum Dots

The fascinating realm of silicon quantum dots (Si QDs) has attracted considerable attention for their exceptional optical characteristics and potential applications in the optoelectronic industry. However, there remains a scarcity of research that directly compares the impacts of diverse surface modification methods on the electronic structure and charge transfer properties of Si QD nanomaterials. Considering this scientific challenge, we employ the first-principle calculations to conduct the following investigations. To begin, we have innovatively introduced the concept of the adjacent coordination number (ACN) to establish a quantitative correlation between the band gap (Eg) and the doping sites of boron (B) atoms across various sizes of Si QDs. Additionally, a combination of Total Density of States (TDOS), Partial Density of States (PDOS) and orbital component analysis reveals that the subtle dipole effect near the B-doping site significantly contributes to the reduction in the band gap, providing valuable insights into the complex impact of different doping sites on the electronic arrangement and structure of Si QDs. Ultimately, our absorption spectroscopy, charge transfer and Quantum Theory of Atoms in Molecules (QTAIM) analysis of organic molecule coupling Si QDs reveal the formation of dipoles on the surface and the correlation between charge migration direction and binding sites. This phenomenon not only amplifies the presence of conjugated coupling states but also significantly enhances the charge transfer capability of Si QDs. These valuable insights will provide significant advantages to scientists and researchers endeavoring to tailor the electronic structure and optical attributes of Si QDs using a diverse array of modification techniques to meet specific application requirements.Graphical AbstractThe surface functionalization of Si QDs involves doping or coupling site selection and the establishment of charge transfer bridges is crucial for the formation of dipole-dipole interaction which may not only play a role in regulating band gap structures but also exert significant control over the charge transfer capacity of Si QDs.