Disulfide-Bond-Containing Polyurethane as an Interface Layer for Efficient and Stable Antimony Selenosulfide Solar Cells

Antimony selenosulfide (Sb2(S,Se)3) is an emerging photovoltaic light-harvesting layer material due to its optoelectronic properties, high absorption coefficient, low preparation cost, and high environmental sustainability. However, during the device fabrication of Sb2(S,Se)3 solar cells, a large number of defects are prone to form on the surface and interface of the film, leading to aggravated nonradiative carrier recombination, which severely restricts the improvement of device photovoltaic performance. Herein, a disulfide-bond-containing polyurethane (SSPU) is introduced as a dynamic polymeric interfacial layer for Sb2(S,Se)3 solar cells. Benefiting from the synergistic chemical coordination of polar N/O groups with surface Sb atoms and thermally activated disulfide bond rearrangement, SSPU simultaneously passivates surface dangling bonds and relieves grain-boundary stress in Sb2(S,Se)3 thin films. This dual-function modulation effectively suppresses nonradiative carrier recombination and facilitates interfacial charge transport, leading to a pronounced open-circuit voltage enhancement from 0.462 to 0.493 V and a champion power conversion efficiency of 8.28%. This work demonstrates a dynamic polymer-enabled interface engineering strategy for antimony chalcogenide photovoltaics.