Magnetic‐Field Modulation of Charge Transport in Non‐Fullerene Semiconductors for Enhanced Hydrogen Evolution

This study demonstrates that weak magnetic fields (16–40 mT) increase the efficiency of the hydrogen evolution reaction (HER) in electrocatalysts based on non‐fullerene acceptor (NFA) derivatives IT‐4Cl and Y6. Electrochemical measurements reveal that the application of the magnetic field reduces the onset potential and increases the current density, with the effect being more pronounced and persistent in IT‐4Cl. The increase is attributed to the synergistic action of the magnetohydrodynamic effect (MHD), which improves mass transport, and the magnetochemical effect (MCE), which modulates spin‐dependent processes. Electron paramagnetic resonance (EPR) analyses confirm a higher polaron density in IT‐4Cl, while Raman spectroscopy indicates that this material is structurally more responsive to the magnetic field, exhibiting band broadening and frequency shifts. These results show that weak magnetic fields induce electronic and structural modifications, favoring charge separation. This work establishes magnetic field assistance as a promising strategy to optimize HER performance in organic semiconductors, reducing dependence on precious metal catalysts and promoting a more sustainable route for hydrogen production.