Multilevel (or multistate) electrochromic devices have the potential to achieve highly compact memory capacity while instantaneously transferring data between memory and processing units. In this article, three novel solution‐processable ruthenium‐polymetallaynes (i.e., P1, P2, and P3), in which the redox‐addressable Ru center is covalently embedded into a conjugated organic polymer, are discussed. In pursuit of higher functionality (e.g., stable multistate behavior, low operating voltage), the organic ligand bridging the metal centers is systematically varied. The previously reported P1 has a bithiophene (BT) bridging ligand with a high degree of rotational freedom. By replacing BT with cyclopenta‐dithiophene in P2 and dithieno‐pyrrole (DTP) in P3, both of which are more planar than BT, the degree of freedom is decreased. By using DTP, redox‐matching is achieved between the metal center and organic ligand, leading to extra stability of the mixed‐valence (MV) state in P3. In‐depth experimental (i.e., in situ electron paramagnetic resonance and UV–vis–NIR spectroelectrochemistry) and theoretical studies (i.e., DFT calculations) are carried out on the polymer thin‐films, showing enhanced metal–metal (M–M) interaction in P2 and P3 and stable Robin–Day class III MV compound in P3. These polymers are also first time fabricated into solid‐state electrochromic devices and the stability of each oxidation state is characterized by tracing the change of transmittance over time, showing satisfactory cyclic stability and retention behavior (≈90% retention after 30 min).

Newly designed push−pull ligands (L1 and L2) with bithiophene (bth) as a donor and phenazine (phz) or quinoxalino [2,3-b]quinoxaline (qxq) as acceptors were synthesized and also incorporated with a bipyridyl Ru(II) complex to give Ru1 and Ru2, respectively. The ultrafast photophysical dynamics of the ligand and their respective Ru(II) complexes were well-characterized using time-resolved spectroscopies and quantum chemical calculations. Photoinduced charger transfer (CT) and intersystem crossing (ISC) processes were directly observed for L1 and L2. In addition, the interplay of three different triplet excited states was directly observed in the related Ru(II) complexes. The lowest-lying triplet excited states of the ligands and their respective Ru(II) complexes were both attributed to the CT transitions from donor (bth) to acceptor (phz or qxq) and result in 3 ICT (intramolecular charge transfer) and 3 ILCT (intraligand charge transfer) excited states, respectively. The lifetimes of the lowest-lying triplet excited states of L1, L2, Ru1, and Ru2 were measured to be 21.3, 50.4, 2.75, and 4.16 μs, respectively.

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