All-optical manipulation of singlet exciton transport in individual supramolecular nanostructures by triplet gating

Molecular design and functional outcomes of RTP and TADF traits in isomers

This study reports the synthesis and photophysical analysis of three isomeric compounds, namely 3Fmo, 3Fmm, and 3Fmp, which were engineered using carbazole as the electron donor, phthalimide as the electron acceptor, and a benzene ring as the bridging moiety. Among these, 3Fmm was distinguished by its ability to exhibit immediate room-temperature white phosphorescence following the cessation of UV illumination, whereas 3Fmo and 3Fmp demonstrated TADF properties. Crystallographic analysis revealed unique intermolecular π-π stacking interactions within 3Fmm, absent in the other two isomers. Advanced TD-DFT computations indicated that such π-π stacking in 3Fmm not only facilitates intersystem crossing but also effectively reduces the free volume within the crystal, leading to a decrease in non-radiative transitions. These molecular interactions promote the manifestation of room-temperature phosphorescence. Furthermore, leveraging the superior luminescent properties of 3Fmo, the compound was successfully utilized in cellular imaging, where it achieved excellent imaging results, showcasing its potential for biomedical applications.

Spatial Correlations Drive Long-Range Transport and Trapping of Excitons in Single H-Aggregates: Experiment and Theory

Describing long-range energy transport is a crucial step, both toward deepening our knowledge on natural light-harvesting systems and toward developing novel photoactive materials. Here, we combine experiment and theory to resolve and reproduce energy transport on pico- to nanosecond time scales in single H-type supramolecular nanofibers based on carbonyl-bridged triarylamines (CBT). Each nanofiber shows energy transport dynamics over long distances up to ∼1 μm, despite exciton trapping at specific positions along the nanofibers. Using a minimal Frenkel exciton model including disorder, we demonstrate that spatial correlations in the normally distributed site energies are crucial to reproduce the experimental data. In particular, we can observe the long-range and subdiffusive nature of the exciton dynamics as well as the trapping behavior of excitons in specific locations of the nanofiber. This trapping behavior introduces a net directionality or asymmetry in the exciton dynamics as observed experimentally.