Strong Chelating Additive and Modified Electron Transport Layer for 8.26%-Efficient Sb2S3 Solar Cells

Abstract

Antimony sulfide (Sb₂S₃) is a promising absorber for single-junction and tandem solar cells. Unfortunately, its quasi-1D structure holds large void space and complex deep defects, which prepare high-quality absorber layers and pose a significant challenge. In this work, ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) is developed as an additive to regulate the reaction kinetics for Sb₂S₃ deposition. The strong chelating interaction between EDTA-2Na and Sb³⁺ significantly suppresses homogeneous nucleation byproducts and retards the deposition rate of the absorber layer. On the other hand, the SnO₂/CdS double buffer layers could enhance light transmittance, and herein NH₄F is successfully applied to improve the dispersion of SnO₂ nanoparticles and increase the n-type conductivity of SnO₂ film through fluorine doping. Finally, the resulting Sb₂S₃ solar cells obtained significantly improved fill factor (FF) and short circuit current density (J_SC) values of 64.81% and 17.91 mA cm⁻², and its power conversion efficiency (PCE) reached a new record value of 8.26% (8.08% certified). This work offers new insights into addressing key challenges that hinder the development of Sb₂S₃ solar cells.