Decoupling 2D Inter- and Intrachain Energy Transfer in Conjugated Polymers

Intercalation in layered SnS2 of blue‐emitting polyfluorene chains with known concentrations of fluorenone sterically hinders 3D polymer aggregation and π–π interchain interactions. Monitoring the fluorene‐to‐fluorenone energy transfer in quasi‐2D polymer monolayers (see schematic diagram) reveals that 2D energy transfer in conjugated polymers is mainly an interchain process. The dimensionality of conjugated polymer systems plays an important role in energy‐transfer processes, and 1D and 2D energy transfer of excitations are typically much slower than that between π‐stacked chains within a 3D polymeric solid. However, whether 2D energy transfer in conjugated polymers occurs mainly along polymer chains (intrachain), or between in‐plain‐adjacent polymer chains (interchain), has yet to be determined due to the difficulty of experimentally decoupling inter‐ and intrachain interaction in a 2D polymer system. This can be achieved by incorporating conjugated polymer chains into the planar galleries of layered matrices which sterically hinder polymer aggregation and π–π interchain interactions. Here, pristine blue‐emitting polyfluorene chains and polyfluorene chains with known concentrations of green‐emitting on‐chain fluorenone defects are either separately or collectively incorporated into layered SnS2. X‐ray powder diffraction of the composite films confirms incorporation of the polymer chains into the layered galleries. Monitoring the fluorene‐to‐fluorenone energy transfer as a function of fluorenone concentration and distribution in the layered galleries allows differentiation between inter‐ and intrachain fluorene–fluorenone energy transfer. It is found that, 2D energy transfer in conjugated polymers follows mainly an interchain process, despite the absence of π–π interchain interactions. Intercalation in layered SnS2 of blue‐emitting polyfluorene chains with known concentrations of fluorenone sterically hinders 3D polymer aggregation and π–π interchain interactions. Monitoring the fluorene‐to‐fluorenone energy transfer in quasi‐2D polymer monolayers (see schematic diagram) reveals that 2D energy transfer in conjugated polymers is mainly an interchain process.