Knowledge of the charge (electron) transfer process at the donor-acceptor interface is required to understand the working mechanisms of different organic photovoltaic materials. Investigating the lowest charge-transfer state in organic donor-acceptor solar cells is important as it allows the destruction/formation of excitons and polarons to be studied, and is directly related to the open circuit voltage. By performing low-cost and feasible calculations of ground-state electronic structures using the Mulliken rule as well as the optimally tuned range-separated hybrid (OTRSH) density functional and a regular long-range corrected functional, the lowest charge-transfer (CT) state energies of a series of dimers containing functionalized anthracene (the donor) and tetracyanoethylene (the acceptor) were obtained. The jumping distances of excited electrons during CT were calculated. The polarizable continuum model was applied to account for the effects of the solvent methylene chloride (CHCl) on the lowest CT state energies obtained from gas-phase calculations. The calculated lowest CT state energies of the dimers were close to the corresponding experimental results, with a root mean square deviation (RMSD) of 0.22 eV.
Solid-state hydrogen storage may be the only promising way for mobile applications of hydrogen energy since it is safe, quickly reversible, cost-efficient, and has a high volumetric energy density under standard conditions. Silsesquioxane and its derivatives seem well suited for solid-state hydrogen storage and have attracted many experimental and theoretical researchers. In the present work, we have systematically studied four cages of T8, T10, and T12 (D 2d and D 6h ) for hydrogen storage including adsorption and encapsulation of hydrogen molecules. We find that silsesquioxane cages have up to about 4150 m 2 /g specific surface area (SSA) and 7.81 wt % for hydrogen storage. These calculated values are comparable to the highest hydrogen storage values of metal−organic frameworks, porous polymer networks, and covalent organic frameworks. In addition, we use the quasi-dynamic method to study the encapsulation of hydrogen molecules into these cages because of the timescale limitation of ab initio molecular dynamics. Thermodynamic parameters such as enthalpy and Gibbs free energy at different temperatures are calculated during the insertion processes. We find that the insertion process of a hydrogen molecule into the T12 (D 6h ) cage is almost energy-conserved and its energy barriers of enthalpy and free energy are moderate under standard conditions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.