Ground-State Charge Generation-Enabled Nondestructive Defect Passivation in Organic Photovoltaics

Ground-state charge generation (GSCG) offers a potent yet underexplored avenue for trap engineering in organic solar cells (OSCs), provided it can be harnessed without disrupting the bulk heterojunction morphology. Herein, we demonstrate an efficient GSCG strategy via FeCl₃ doping in the polymer donor D18, achieving a paradigm of "nondestructive defect passivation." Mechanistically, the GSCG-induced trap filling operates in the pre-excitation ground state, effectively neutralizing deep-level defects without compromising the donor-acceptor interfacial integrity. Ultrafast spectroscopy reveals that this ground-state premodulation selectively optimizes photophysical dynamics: while preserving efficient exciton dissociation, it profoundly suppresses nongeminate recombination and blocks the energy-loss channel associated with triplet exciton formation. Consequently, the optimized devices deliver a remarkable open-circuit voltage of 0.917 V and a photoelectric conversion efficiency of 20.67%. This work elucidates the mechanism of morphology-compatible defect passivation, establishing GSCG as a critical lever for minimizing energy loss in high-performance OSCs.