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

A bifunctional Ru-II 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.