Browsing by Author "Khandelwal, V."

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    Graphene Straintronics by Molecular Trapping
    (American Chemical Society, 2025) Srivastava, P.K.; Khandelwal, V.; Reddy, I.R.; Tarafder, K.; Ghosh, S.
    Here, we report on controlling strain in graphene by trapping molecules at the graphene–substrate interface and leveraging molecular dipole moments. Spectroscopic and transport measurements reveal that strain correlates with the dipole moments of trapped molecules extending beyond their molecular sizes, where values ranging from 1.5 to 4.9D lead to a 50-fold increase in strain and a significant rise in residual carrier density. This has been possible by charge transfer between graphene and trapped molecules, altering the C?C bond length and causing biaxial strain. First-principles density functional theory calculations confirm a consistent dependence of the bending height on molecular dipole moments. © 2025 American Chemical Society
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    Revealing the Microscopic Picture of the Charge Transfer Mechanism between Graphene and Dopant Molecules
    (American Chemical Society, 2023) Khandelwal, V.; Srivastava, P.K.; Nagaraja, S.; Yadav, P.; Tarafder, K.; Ghosh, S.
    It is generally recognized that the dipole moment of the adsorbed molecules is a crucial factor in determining the charge-transfer interaction between molecules and graphene. However, the microscopic details of this process have remained elusive. In this study, we experimentally investigate the charge-transfer interaction between adsorbed molecules and graphene, which holds great promise for achieving controllable doping. By trapping various molecules at the graphene-substrate interface, our results emphasize that the doping effect primarily depends on the reactivity of the constituent atoms in the attached molecules rather than just their dipole moment. Observation of (i) the emergence of the Raman D peak exclusively at the edges for trapped molecules without reactive atoms, and throughout the entire basal plane for those with reactive atoms, and (ii) variations in the density of attached molecules (with and without reactive atoms) to graphene with their respective dipole moments provides compelling evidence to support our claim. These findings are well-supported by experimental results and first-principles density functional theory calculations. © 2023 American Chemical Society.