Atomic-Scale Defect Reconfiguration via Thermally Induced Structural Ordering for High-Efficiency Sb₂Se₃ Solar Cells

Area of Science:

• Materials Science
• Solid-State Physics
• Photovoltaics

Background:

• Antimony triselenide (Sb₂Se₃) thin-film solar cells are hindered by deep-level defects.
• Structural disorder in Sb₂Se₃ limits carrier lifetimes and photovoltaic performance.

Purpose of the Study:

• To investigate a thermodynamically driven disorder-to-order transition in Sb₂Se₃ thin films.
• To enhance Sb₂Se₃ solar cell performance through defect passivation and microstructural reconstruction.

Main Methods:

• Solution-processable MgCl₂ treatment for defect passivation.
• First-principles calculations to understand ion-vacancy interactions.
• Analysis of microstructural reconstruction and carrier lifetime measurements.

Main Results:

• MgCl₂ treatment passivates Sb and Se vacancies, reducing antisite defects.
• Metastable intermediates accelerate microstructural reconstruction to form single crystals.
• Trap density reduced 10-fold, extending photocarrier lifetimes significantly.
• Achieved a certified Sb₂Se₃ solar cell efficiency of 9.31%.

Conclusions:

• Synergistic ionic and structural changes improve Sb₂Se₃ photovoltaic performance.
• The study provides a generalizable pathway for improving low-dimensional photovoltaics.