Bismuth Complex Controlled Morphology Evolution and CuSCN-Induced Transport Improvement Enable Efficient BiI₃ Solar...

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Bismuth triiodide (BiI₃) is a low-cost, non-toxic material for thin-film solar cells.
• Film morphology significantly impacts BiI₃ solar cell efficiency by influencing trap states.

Purpose of the Study:

• To control BiI₃ film morphology using a coordination engineering strategy.
• To enhance the photovoltaic performance of BiI₃-based solar cells.

Main Methods:

• Coordination engineering with dimethyl sulfoxide (DMSO) to form BiI₃(DMSO)₂ complex.
• Density functional theory (DFT) calculations to understand complex interactions.
• Fabrication of thin films and solar cells using copper(I) thiocyanate (CuSCN) as a hole transport layer.

Main Results:

• Formation of a stable BiI₃(DMSO)₂ complex.
• Fabrication of uniform, pinhole-free BiI₃ films with preferred crystallographic orientation.
• Reduced trap densities, suppressed charge recombination, and improved carrier mobility.
• Achieved a record power conversion efficiency of 1.80% and a fill factor of 51.5%.

Conclusions:

• Coordination engineering with DMSO effectively controls BiI₃ film morphology.
• High-quality BiI₃ films lead to enhanced solar cell performance.
• This strategy offers a pathway for further improvements in BiI₃ solar cell technology.