Full‐Dimensional Penetration Strategy with Degradable PEAI Enables 8.21% Efficiency in Bulk Heterojunction Sb₂S₃ Solar Cells

Abstract Antimony trisulfide (Sb 2 S 3 ) is a promising low‐cost photovoltaic material, but practical Sb 2 S 3 solar cells suffer from multiple defects, anisotropic transport, and interfacial energy‐level mismatches, limiting power conversion efficiency ( η ) to 6%‐7%. Herein, a degradable full‐dimensional penetration passivation strategy using phenethylammonium iodide (PEAI) is proposed to synergistically address these issues. PEAI pretreatment of amorphous Sb 2 S 3 films enables [ hk 1]‐oriented crystallization, full‐dimensional defect passivation (bulk and interfaces), and dual‐interface energy‐level reconstruction via Cd‐I and Sb─I bonding. The PEAI reduces CdS surface energy and preferentially adsorbs on Sb 2 S 3 (211) planes, promoting [ hk 1] orientation and enhancing carrier transport. Moreover, the penetrated PEAI leads to a 3.7‐fold increase in carrier lifetime, verifying effective defect suppression. The resultant bulk heterojunction (BHJ) solar cells achieve a η of 8.21%, which is the highest efficiency of BHJ Sb 2 S 3 solar cells. This work establishes a quadruple‐integrated paradigm (defect passivation, orientation control, energy‐level optimization, and architecture design), providing a universal roadmap for high‐efficiency, sustainable photovoltaics.