A Mixed-Pure Planar Heterojunction Structure of Active Layers for Efficient Sequential Blade-Coating Organic Solar...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Achieving high power conversion efficiencies (PCEs) in organic solar cells (OSCs) relies on precise control of active layer vertical structure to enhance charge transfer.
• Developing efficient and scalable fabrication methods is crucial for commercializing OSCs.

Purpose of the Study:

• To investigate the effect of processing solvents on the vertical structure of active layers in OSCs fabricated using sequential blade-coating (SBC) technology.
• To establish a solvent-regulating method for optimizing active layer microstructure and boosting OSC performance.

Main Methods:

• Fabrication of OSCs using a rapid film-forming method combining low boiling point solvents and SBC technology.
• Characterization of active layer vertical structure using grazing incident wide-angle X-ray scattering (GIWAXS) and tilt resonant soft X-ray scattering (T-RSoXS).
• Device performance evaluation to determine power conversion efficiencies (PCEs).

Main Results:

• Processing solvents significantly influence the vertical component distribution within the active layers.
• Dichloromethane (DCM)-processed films exhibit a truly planar heterojunction structure.
• Chloroform (CF)-processed upper layers create a larger mixed-phase region, leading to improved charge generation and a superior PCE of 17.36%.
• DCM-processed devices achieved the highest PCE (16.66%) for truly planar heterojunctions, indicating high morphological tolerance.

Conclusions:

• Solvent selection is a critical factor in controlling the vertical microstructure of active layers fabricated via SBC.
• The proposed solvent-regulating method via SBC offers practical guidance for optimizing OSC active layer morphology and enhancing device efficiency.
• This approach demonstrates a viable strategy for fabricating high-performance organic solar cells.