The Role of Terminal Fluorination on Energy Inversion in Organic Solar Cells

Abstract Suppressing non‐radiative energy loss (Δ E 3 ) mediated by the triplet charge transfer state is crucial for high‐performance organic solar cells (OSCs). Here, we decode the energy inversion through multi‐scale theoretical simulations, which inhibit the formation of non‐emissive triplet (T 1 ) state. However, it is mystified by the system dependence. We first demonstrate a direct relationship of “the probability of Face‐on orientation ( P Face‐on ) is proportional to the probability of energy inversion ( P EI )”, which is related to the function of terminal fluorination. Through Pearson′s correlation coefficient and machine learning model, the useful stacking structural parameters were obtained to clarify the effect of π‐bridge group on the function of terminal fluorination. Based on the molecular descriptors established, we explain that the fluorination effect is beneficial to Face‐on orientation and thus energy inversion due to the enhanced intermolecular coupling. But the π‐bridge inhibits this coupling with the interfacial stacking configuration appearing more “TT_IC”. This work provides a directional standard for promoting energy inversion to reduce Δ E 3 for the high‐performance OSCs.