Defect Passivation of Efficient Sb2(S,Se)3 Solar Cells with Ultrathin, Insulating Polymers

Interfacial passivation is an effective strategy to suppress recombination and improve the stability of efficient solar cells. Here, Sb 2 (S,Se) 3 , a promising candidate for next‐generation, solution‐processed photovoltaics, is carefully studied focusing on the defect state distribution and recombination mechanism. Ultrathin polymer layers were introduced to the n‐i‐p Sb 2 (S,Se) 3 thin‐film solar cells. The insulating polymers can effectively fill the grain boundaries and pinholes, which physically restrain the leakage channels in the film and reduce the surface roughness. By adding this passivation layer, the device exhibits fewer interface states while spatially separating electron holes localized at the interface. The average fill factor of these optimized devices presents an 8% improvement, compared with the control devices. The maximum efficiency reaches a state‐of‐the‐art efficiency of 8.9%. These results again prove the concept of metal‐insulator‐semiconductor, and revealed the mechanism of polymer passivation enhanced photovoltaic performance.