Hybrid Structure of Ionic Liquid and ZnO Nano Clusters for Potential Application in Dye-Sensitized Solar Cells

"Green processes" for the production of renewable energy such as the utilization of solar energy would decisively help to avoid depletion of resources and environmental degradation. In this connection, we have investigated hy-brid structures of the ionic liquid (IL) 1-ethyl-3-methylimidazolium tetrafluoroborate (C(2)mim BF4) and (ZnO)(n) nano dusters as charge-transfer promoters concerning their application in highly efficient dye-sensitized solar cells (DSSCs) using density functional theory (DFF). Structural properties, frontier molecular orbitals, and energy gaps (E-g) were analyzed to understand the interaction mechanism between the IL and ZnO nano clusters. The in-fluence of (ZnO)(n) nano clusters on electronic properties of the IL was investigated by analyzing electrostatic po-tential (ESP) mapping, work function (phi), and density of states. The highest binding energy between IL and ZnO nano cluster was obtained for the IL/(ZnO)(2) hybrid structure, which has enhanced charge-transfer and a smaller energy gap (3.09 eV) compared to the other considered systems. The photo-energy-conversion efficiencies (eta) of DSSCs based on IL/(ZnO)(n) (n = 2-12) hybrid systems were predicted under irradiance with an air mass 1.5 global (AM 1.5 G) spectrum. Solar parameters such as open-circuit voltage V-OC, fill factor FT, and short-circuit current density J(SC). were determined to evaluate eta. The maximum efficiency (1.96%) is found for the IL/(ZnO)(2) system due to the high short-circuit-current density, improved electron extraction, and low work function, which allows the injection of more electrons into the TiO2 surface. Our results on the hybrid structures of IL and ZnO nano clus-ters reveal a possibility for the design of highly efficient next-generation DSSCs. (C) 2020 Elsevier B.V. All rights reserved.