Precise Morphology Control via Backbone-Derived Solid Additive Enables Binary Organic Solar Cells to Achieve 20%...

Area of Science:

• Materials Science
• Organic Electronics
• Renewable Energy

Background:

• Precise control over the active layer morphology is crucial for the advancement of organic solar cells (OSCs).
• Existing methods for morphology control often lack generalizability for practical applications.
• Developing scalable strategies for high-performance OSCs remains a key challenge.

Purpose of the Study:

• To propose a generalizable strategy for regulating active layer morphology in OSCs.
• To investigate the use of a structurally tailored crystallization template derived from the polymer donor backbone.
• To enhance the power conversion efficiency (PCE) and stability of OSC devices.

Main Methods:

• Design of a small molecule crystallization template (BDD-C6) by extracting units from the polymer donor backbone (PM6).
• Incorporation of BDD-C6 into binary blends (PM6:L8-BO and PM6:BTP-eC9) and evaluation on alcohol-soluble substrates.
• Analysis of compatibility, vertical phase distribution, thermal stability, crystallinity, crystallization kinetics, and morphological characteristics.
• Fabrication and characterization of OSC devices using modified blends and extension to other polymer systems (D18).

Main Results:

• BDD-C6 incorporation led to favorable vertical phase distribution and enhanced thermal stability and crystallinity.
• The template delayed film formation and promoted polymer ordering, extending exciton diffusion length.
• PM6:L8-BO based devices achieved PCEs of 19.81% (thin film) and 16.93% (400 nm thickness).
• PM6:BTP-eC9 based OSCs exceeded 20% efficiency.
• The strategy was successfully extended to D18 systems, achieving a 20.18% PCE in D18:L8-BO devices.

Conclusions:

• The backbone-derived crystallization template strategy is effective for regulating OSC morphology.
• This approach enables scalable fabrication of high-efficiency organic solar cells.
• The method offers a promising pathway for advancing OSC technology toward commercial viability.