Unraveling Ground-State Electron Transfer in Photoredox n-Doping of Conjugated Polymers through Real-Time Quantum...

We recently demonstrated that photoredox catalysts can enable n-type doping of conjugated polymers under light at room temperature. While experimental data confirm that the key electron transfer step can proceed from the photoredox catalyst to the conjugated polymer without the involvement of a second photon, a pathway typically invoked to access highly polarized excited states, the underlying mechanism remains elusive. In this work, we employ real-time quantum electron dynamics to investigate the fundamental mechanisms governing this specific charge transfer process and its dependence on the geometric orientation. Our energetic analysis reveals that while this charge transfer process from the photoredox catalyst to the conjugated polymer is thermodynamically favorable, it is only kinetically accessible via through-space charge transfer in a limited set of orientations between the photoredox catalyst and the conjugated polymer. To further enhance the doping efficiency, we propose applying an external static field along the electron transfer direction. Quantum dynamic simulations demonstrate that such an external bias suppresses the tunneling barrier, leading to a faster and more efficient charge transfer. These findings provide valuable design principles for optimizing molecular doping strategies, highlighting the role of structural packing and external field modulation in improving the charge injection and transport in organic electronic materials.