Polymeric Hydrogen-Bonding Control of Photoinduced Electron Transfer in Dye–CaTiO3 Hybrids

We report that poly(vinyl alcohol) (PVA) matrices facilitate nanosecond photoinduced electron transfer (PET) from cyanine dyes to CaTiO3 nanocrystals, yielding distinct radical cation excited-state absorption (ESA) with well-resolved D0→D1 and D1→D2 transitions. In dye-only PVA films, UV hole-burning produces a minority radical cation population, evidenced by a blue-shifted ESA band mirroring the D1→D2 manifold. Kinetic analysis of the ternary PVA–dye–CaTiO3 system reveals a shared nanosecond decay (τ2 ≈ 4–7 ns) for both oxide ESA and radical cation transitions, confirming coupled charge-separated states. These results establish orbital-level insight into how polymer matrices regulate PET and radical stabilization, providing a mechanistic foundation for programmable hybrid photonic devices.