Zn doping modulation of carrier transport properties at the back interface of antimony sulfide solar cells

Abstract

Sb₂S₃ has emerged as a highly promising material for thin-film solar cells due to its low toxicity, excellent stability, and strong light absorption in the visible region. However, challenges such as the formation of the Sb₂O₃ secondary phase and S re-evaporation still exist during the high-temperature annealing of Sb₂S₃. To address these issues, this study introduces a strategy involving the pre-deposition of an ultrathin ZnO protective layer onto the Sb₂S₃ surface. The ZnO layer facilitates controlled oxygen passivation through a lattice-vacancy-mediated mass transfer mechanism, effectively suppressing the formation of Sb₂O₃ and minimizing Sb₂S₃ volatilization, while simultaneously forming a Zn-doping layer. The results show that Zn doping significantly enhances the energy level alignment at the back interface: the conduction band minimum (CBM) and valence band maximum (VBM) of the Sb₂O₃/Sb₂S₃ mixed layer are upshifted, and the Fermi level is downshifted, thereby promoting hole transport. Additionally, the carrier concentration increases, reducing the contact barrier with the carbon electrode. This modification enables the power conversion efficiency (PCE) of all-inorganic Sb₂S₃ solar cells with fluorine-doped tin oxide (FTO)/CdS/Sb₂S₃/PbS/Carbon/Ag structures to reach an impressive 7.00%, representing the most advanced performance level currently available and providing new guidance for the development of high-performance and low-cost all-inorganic Sb₂S₃ solar cells.

Keywords

Sb₂S₃ solar cells / Zn doping / interface engineering / carrier transport

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