Electronic and Optical Property Modulation in Belt[15]Pyridine–Fullerene Nano‐Saturn Complexes

ABSTRACT For the modification of energy gaps and electronic characteristics of materials used in optoelectronic devices, doping is widely employed. The physisorption and chemisorption processes are responsible for altering HOMO‐LUMO energy gaps. However, precise control over the tuning of HOMO and LUMO levels in the doped systems remains a challenge. Hence, the need arises for systems enabling the precise adjustment of energy gaps and the HOMO and LUMO levels. Herein, the Saturn‐like host–guest systems based on the nitrogen‐doped carbon nanobelt (belt[15]pyridine or BP) and fullerenes (C 20 , C 32 , C 34 , and C 36 ) are explored to study the controlled tuning of electronic properties, using density functional theory (DFT) calculations. The greater values of interaction energies ranging from −38.61 to −59.96 kcal/mol reveal the thermodynamic stability of the designed host–guest complexes. The results of frontier molecular orbital (FMO) analysis demonstrate the contribution of the HOMO of fullerenes and the LUMO of BP towards the HOMO and LUMO of the newly designed complexes, respectively, for C 20 @BP and C 36 @BP complexes. The results of FMO are verified through the density of states (DOS) spectra analysis. Furthermore, the charge shift from the host, that is, BP, towards the guest, that is, fullerenes, is proved and justified through natural bond orbital (NBO) and electron density difference (EDD) analyses. Moreover, non‐covalent interaction (NCI) index and quantum theory of atoms in molecule (QTAIM) analyses provide a deeper insight into the nature and extent of interactions present between the fullerenes and the nanobelt, verifying that the prominent interactions are van der Waals forces. The more pronounced van der Waals interactions are noticed for the C 34 @BP complex. Moreover, it is observed through UV‐Vis analysis that the isolated fullerenes show the absorption maxima in the UV region, but after encapsulation of fullerenes inside BP, three of the designed complexes show maximum absorption in the near infrared (NIR) region, with absorption maxima ( λ max ) ranging from 1100 to 1149 nm; hence, they can be employed for various applications. Overall, our analyses highlight the design of nano‐Saturn complex systems and the controlled tuning of the electronic properties in these systems through the tuning of HOMO and LUMO levels selectively over the fullerenes and BP. Hence, the judicious selection of system with desired band gap is possible by careful selection of host and guest.