Characterising Exciton Generation in Bulk-Heterojunction Organic Solar Cells

Area of Science:

• Optoelectronics
• Materials Science
• Renewable Energy

Background:

• Organic solar cells (OSCs) are promising for renewable energy.
• Bulk-heterojunction (BHJ) architecture is key to OSC performance.
• Exciton generation dynamics are critical for efficient charge separation.

Purpose of the Study:

• To characterize exciton generation in three types of BHJ OSCs.
• To determine the optimal active layer thickness for maximum exciton generation.
• To investigate the impact of layer thicknesses on photovoltaic performance.

Main Methods:

• Simulated exciton generation rates (total and position-dependent).
• Analyzed optical properties (light absorption and electric field interference).
• Optimized layer thicknesses for three BHJ OSC architectures.

Main Results:

• Exciton generation strongly depends on active layer thickness due to optical interference.
• An optimal thickness maximizes the overlap between high absorption and constructive interference regions.
• Inverted non-fullerene BHJ OSCs demonstrated superior short-circuit current density.

Conclusions:

• Optimal active layer thickness is crucial for efficient exciton generation in BHJ OSCs.
• Inverted non-fullerene BHJ OSCs offer potential for enhanced photovoltaic performance.
• Findings provide guidance for fabricating efficient and cost-effective BHJ OSCs.