Extending Long‐lived Charge Separation Between Donor and Acceptor Blocks in Novel Copolymer Architectures Featuring a Sensitizer Core

A bifunctional RuII photosensitizer unit was decorated with one n‐ and one p‐type polymer chain to form precisely controlled hierarchical copolymer‐type architectures for light‐induced charge separation. The applied modular chemistry‐on‐the‐complex strategy benefits from separately prepared building blocks and their orthogonal linkage in the two final assembly steps. Upon visible light absorption, electron transfer is initiated between the conjugated poly(3,6‐carbazole) chain and the styrenic poly(naphthalene diimide) segments. Steady‐state and time‐resolved spectroscopy show complete charge separation within a few nanoseconds (>95 % efficiency) persisting several tens of microseconds. The recombination is significantly reduced in comparison to low‐molecular model systems or to non‐conjugated congeners, reflecting the higher charge mobility in conjugated polymers. In summary, the modularity of the presented approach is expected to serve as a versatile platform to tailor the interface between the charge transport domains in a systematic fashion. A copolymer‐type photosystem was assembled from a RuII photosensitizer core with pendant redox‐active and conjugated electron donor and acceptor polymers. The polymer blocks are designed to facilitate directional light‐induced charge separation. The utilization of a conjugated polymer demonstrates the highly efficient formation and extension of the charge separation lifetime, as detailed by transient absorption and emission spectroscopy.