Long-Lived Charge-Transfer State and Interfacial Lock in Double-Cable Conjugated Polymers Enable Efficient and Stable...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Donor/acceptor (D/A) interfaces in bulk heterojunction (BHJ) organic solar cells (OSCs) are critical for exciton dissociation and molecular diffusion, impacting device efficiency and stability.
• Optimizing these interfaces is key to advancing OSC technology.

Purpose of the Study:

• To design and investigate a double-cable conjugated polymer, SC-1F, as an interfacial modifier in BHJ OSCs.
• To enhance the efficiency and long-term stability of organic solar cells through interface engineering.

Main Methods:

• Synthesis of the double-cable conjugated polymer SC-1F.
• Incorporation of SC-1F into a PM6:BTP-eC9 blend to form a ternary BHJ system.
• Characterization of the interfacial properties, charge generation, and device performance (PCE, T80 stability).

Main Results:

• SC-1F spontaneously segregates to the D/A interface, forming a favorable interface with the acceptor.
• The long-lived charge-transfer (CT) state of SC-1F (>3 ns) enhances charge generation, boosting PCE from 19.00% to 20.12%.
• SC-1F acts as an 'interfacial lock,' preventing donor and acceptor aggregation under thermal stress, significantly improving T80 stability (2175 h vs. 530 h at 65 °C) and storage stability (>10,000 h).

Conclusions:

• Double-cable conjugated polymers are effective third components for optimizing D/A interfaces in OSCs.
• SC-1F significantly enhances both the power conversion efficiency and the operational/storage stability of organic solar cells.
• This work presents a promising strategy for developing highly efficient and durable organic solar cells.