Unsubstantiated Anomalous Electron Doping in CdS via Cu Substitution for Cd

In a recent article, Mo et al. primarily attributed the enhanced Sb 2 Se 3 solar cell efficiency to anomalous electron doping in the CdS buffer layer via Cu substitution for Cd, reporting unprecedented n ‐type carrier concentrations (>10 20 cm ‒3 ). This Comment challenges the core validity of this attribution by revealing critical inconsistencies: 1) the reported carrier concentrations exceeding literature values for CdS buffer layers by orders of magnitude, aligning with transparent conductive electrodes; 2) Cu substitution for Cd substitution (confirmed by X‐ray diffraction) theoretically acting as a deep acceptor, which suppresses n ‐type semiconductivity via electron trapping; 3) quantitative dopant analysis and Hall effect measurement details—essential to substantiate doping effects—are omitted. The anomalous doping mechanism remains unsubstantiated, urging a paradigm shift in understanding efficiency drivers in Sb 2 Se 3 solar cells with Cu‐doped CdS buffer layers.