Photoinduced charge transfer assisted through external electric field and ternary hydrogen bonding strategies

Understanding the mechanisms governing interfacial charge transfer in photoactive layer is crucial for optimizing photogenerated charge separation efficiency. In this study, the interfacial charge transfer process is regulated by applying external electric field (F_ext) and ternary hydrogen bonding strategies. We observe significant changes in the excited state properties and charge transfer parameters at the interface under F_ext conditions. This facilitates an in-depth exploration of the effects of F_ext on the microscopic details of the interface at the molecular level. Implementing the ternary hydrogen bonding strategy significantly enhances the electron-attracting ability of fullerene. Comparative analysis of the PTB7-Th:PC₇₁BM and PTB7-Th:C7:PC₇₁BM systems under F_ext = 0, reveals that the ternary hydrogen bonding strategy increases the charge transfer pathway and significantly improves the intermolecular charge separation rate (K_CS). Additionally, we evaluated the relationship between hydrogen bond strength and F_ext, demonstrating that F_ext significantly enhances the hydrogen bond strength between C7:PC₇₁BM. These studies provide deeper insights into the role of F_ext and ternary hydrogen bonding strategies in charge transfer process, providing a valuable theoretical framework for designing more efficient organic solar cells (OSCs).