Universal and versatile morphology engineering via hot fluorous solvent soaking for organic bulk heterojunction

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic solar cells (OSCs) have shown rapid efficiency gains, but achieving optimal bulk heterojunction morphology is critical for commercialization.
• Current methods for morphology control face challenges in terms of efficiency and applicability across diverse material systems.

Purpose of the Study:

• To develop a new method for optimizing the morphology of the active layer in organic solar cells.
• To demonstrate the effectiveness of this method across various donor/acceptor combinations in OSCs.

Main Methods:

• A "hot fluorous solvent soaking" method was developed, utilizing the amphiphobic and temperature-dependent miscibility properties of fluorous solvents.
• Blend films were immersed in hot fluorous solvent to accelerate molecular reorganization and optimize morphology.
• The method was tested with polymer/small-molecule, all-polymer, and all-small-molecule OSC systems.

Main Results:

• The hot fluorous solvent soaking method effectively optimized bulk heterojunction morphology in various OSC systems.
• This approach accelerated molecular reorganization by using the fluorous solvent as a thermally conductive medium and a co-solvent with processing residues.
• Photovoltaic performance was superior compared to traditional thermal annealing, achieved under mild processing conditions.

Conclusions:

• The hot fluorous solvent soaking method is a practical and universal approach for morphological optimization in organic solar cells.
• This technique shows significant potential for advancing OSC technology towards consumer market viability.
• The method's effectiveness suggests applicability to other optoelectronic devices requiring precise morphology control.