Adding a methyl group to a benzene ring results in the formation of a molecule called toluene. The effect of this substitution on the electronic transport properties of the benzene ring can be analyzed using density functional theory DFT calculations. DFT is a computational method used to study the electronic structure of molecules and materials, which can provide insights into their electronic transport properties.When a methyl group is added to a benzene ring, the electron-donating nature of the methyl group causes the electron density to be redistributed within the aromatic ring. This results in an increased electron density around the carbon atoms adjacent to the methyl group, making the ring more electron-rich. Consequently, the highest occupied molecular orbital HOMO and the lowest unoccupied molecular orbital LUMO energy levels are altered, which can affect the electronic transport properties of the molecule.In terms of organic electronic devices, the electronic transport properties of a material are crucial for its performance. Materials with suitable HOMO and LUMO energy levels can facilitate charge transport, leading to better device performance. The increased electron density in toluene, as compared to benzene, can potentially improve its performance in organic electronic devices, such as organic field-effect transistors OFETs , organic light-emitting diodes OLEDs , and organic photovoltaics OPVs .However, it is important to note that the effect of adding a methyl group to a benzene ring on its electronic transport properties is just one factor to consider when designing organic electronic devices. Other factors, such as molecular packing, film morphology, and intermolecular interactions, also play significant roles in determining the overall performance of the device. Therefore, while DFT calculations can provide valuable insights into the electronic structure of a molecule, a comprehensive understanding of all relevant factors is necessary to optimize the performance of organic electronic devices.