Advanced Modelling of Polyoxometalate Counter-Cations: Bridging Explicit Counter-Cation Inclusion and Solvent Effects for Electronic Applications

This study explores the explicit modeling of polyoxometalate (POM) counter-cations in both solid states and solutions, focusing on their potential for integration into molecular electronics, specifically as components of single-molecule electronic devices. Employing Density Functional Theory (DFT) and the Conductor-like Screening Model (COSMO), our research addresses the challenge of accurately representing the environmental effects on POMs, particularly the influence of counter-cations and solvent molecules. A critical finding of this work is the demonstration that traditional models, like COSMO, often fail to capture the physical distancing effects of solvents, leading to an overestimation of the proximity of counter-cations to POM anions and resulting in over-stabilized frontier orbital energies. By implementing geometry constraints on lithium cations, we achieve a more realistic depiction of POM-cation interactions in solution, enhancing model accuracy. Additionally, our results suggest that explicit counter-cation inclusion is essential for accurate simulations pertinent to POM applications in electronic devices, though it can be computationally intensive in solution environments. This study not only advances the theoretical understanding of POMs but also underscores the need for improved computational strategies to simulate real-world conditions effectively, thereby guiding the development of POM-based electronic components