PO₄³⁻ Tetrahedron Assisted Chelate Engineering for 10.67%‐Efficient Antimony Selenosulfide Solar Cells

Anisotropic carrier transport and deep-level defect of antimony selenosulfide (Sb₂(S,Se)₃) absorber are two vital auses restraining the photovoltaic performance of this emerging thin-film solar cell. Herein, chelate engineering is proposed to prepare high-quality Sb₂(S,Se)₃ film based on hydrothermal deposition approach, which realizes desirable carrier transport and passivated defects by using tetrahedral PO₄ ^3- ion in dibasic sodium phosphate (Na₂HPO₄, DSP). The PO₄ ^3- Lewis structure, on one hand in the form of [(SbO)₃(PO₄)] chelate, can adsorb on the polar planes of cadmium sulfide (CdS) layer, promoting the heterogeneous nucleation, and on the other hand, the tetrahedral PO₄ ^3- inhibits horizontal growth of (Sb₄S(e)₆)_n ribbons due to size effects, thus achieving desirable [hk1] orientation. Moreover, the introduction PO₄ ^3- effectively passivates the antisite defect Sb_S1. These synergistic effects have effectively improved carrier transport and reduced non-radiative recombination of the Sb₂(S,Se)₃ absorber. Consequently, the DSP-modified Sb₂(S,Se)₃ device efficiency increases from 8.59% to 10.67%.