SbSeI and SbSeBr micro-columnar solar cells by a novel high pressure-based synthesis process

Area of Science:

• Materials Science
• Solid-State Physics
• Renewable Energy

Background:

• Van der Waals chalcogenides and chalcohalides offer potential for thin-film photovoltaic (PV) breakthroughs due to earth-abundant, non-toxic components, stability, and high absorption.
• Quasi-one-dimensional (1D) semiconductors, particularly SbSeX chalcohalides beyond Sb2(S,Se)3, remain underexplored for energy generation, despite their promise for wider bandgap tuning and unique properties like ferroelectricity.

Purpose of the Study:

• To synthesize SbSeI and SbSeBr micro-columnar thin films using a novel physical vapor deposition method.
• To investigate the influence of annealing temperature and pressure on micro-columnar structure morphology and growth.
• To fabricate and characterize solar cell prototypes based on these novel materials.

Main Methods:

• Selective halogenation of Sb2Se3 thin films at pressures above 1 atm to produce SbSeI and SbSeBr.
• Controlled annealing processes to tune micro-columnar structure height, density, and morphology.
• Fabrication of substrate-configuration solar cell devices for performance evaluation.

Main Results:

• First-time synthesis of SbSeI and SbSeBr micro-columnar solar cells via selective halogenation.
• Monotonic growth in micro-columnar structure height and density with increasing annealing temperature and pressure.
• Achieved single-crystal SbSeI columns up to 30 μm with tunable morphology.
• Solar cell prototypes demonstrated notable open-circuit voltage (Voc) exceeding 550 mV and a bandgap of 1.8 eV.

Conclusions:

• The selective halogenation method is effective for producing SbSeI and SbSeBr micro-columnar structures for PV applications.
• Optimized annealing conditions allow for control over micro-columnar morphology, crucial for device performance.
• These novel chalcohalide materials show significant promise for next-generation thin-film solar cells, potentially enabling tandem or semi-transparent devices.