Defects Passivation via Potassium Iodide Post-Treatment for Antimony Selenosulfide Solar Cells with Improved Performance

摘要

Antimony selenosulfide (Sb_2(S,Se)_3) has been emerging as a promising lightabsorber in the past few years owing to tunable bandgap (1.1–1.7 eV), highabsorption coefficient (>10~5 cm~(?1)) and excellent phase and environmentalstability. However, the efficiency of Sb_2(S,Se)_3 solar cells lags far behind theShockley–Queisser limit. One of the critical obstacles originates from variousextrinsic and intrinsic defects. They mostly locate in the deep energy levelsand are prone to form recombination centers, inhibiting the improvement ofdevice performance. Herein, surface post-treatment via potassium iodide isintroduced to fabricate high-quality Sb_2(S,Se)_3 films and solar cells. The surfacepost-treatment not only manipulates the crystal growth process to formcompact films with larger grain size but also forms better band alignmentand inhibits the formation of deep-level defects antimony antisite (Sb_(Se)),thus improving the quality of heterojunction. Consequently, the resultantSb_2(S,Se)_3 solar cells achieve a champion power conversion efficiency of9.22%. This study provides a new strategy of passivating deep-level intrinsicdefects via surface post-treatment for high-efficiency Sb_2(S,Se)_3 solar cells.