In 2D metal-organic frameworks (MOFs), charge transport (CT) mechanism is generally based on two descriptions: through-bond and through-space. The former promotes CT via favorable spatial and energetic overlap of the metal and ligand orbitals involved in covalent bonding. The latter enables charge transport via non-covalent interactions (such as π − π stacking). Excimer states, defined as a superposition of Frenkel exciton and transfer integral states, can act as an exciton traps and decrease the quantum yield of device performance. The relative degree to which the Frenkel and transfer states contribute to the excimer depends on the electronic interactions in molecular aggregates as dictated by distance or orientation.<br/>In our work we investigate and quantify on equal footing the relative contributions of Frenkel excitons, transfer integral states and reorganization energy to carrier mobility. Since local and non-local electron-coupling are associated with the modulations in the intra-molecular and inter-molecular vibrational modes, the coherent/incoherent nature of CT may be inferred from the excimer formation, providing valuable insights on the overall stabilization of the system.<br/>Quantities obtained can then used to parametrize the Hamiltonian and analyze the Stokes shift involved in the absorption and emission spectra.

Role of the excimer in charge transport of hybrid semiconductors: gauging the contributions of reorganization energy, Frenkel exciton and transfer integrals in 2D MOFs

ACS Spring Meeting 2021

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