Sequential Processing Leaves Trace A-D-A-type Acceptor as a Bifunctional Buried Interlayer for Efficient and Stable...

Area of Science:

• Materials Science
• Organic Electronics
• Renewable Energy

Background:

• Inverted organic solar cells (OSCs) show promise for stability and scalability.
• Their efficiency is limited by metal oxide transport-layer defects and poor active-layer morphology.
• Existing strategies often fail to address both issues simultaneously.

Purpose of the Study:

• To develop a strategy that simultaneously improves the efficiency and stability of inverted OSCs.
• To address limitations posed by ZnO transport layers and active layer morphology.
• To provide a universal method applicable to various OSC systems.

Main Methods:

• A trace-residual buried interface (TRBI) strategy using a thin A-D-A-type acceptor (L8-BO) layer pre-deposited on ZnO.
• The L8-BO layer passivates ZnO surface defects and induces ordered molecular packing of the acceptor.
• Investigated the impact of TRBI on electron transport, extraction, and device morphology.

Main Results:

• The TRBI strategy significantly improved short-circuit current density and fill factor (FF).
• Achieved a record 18.7% power conversion efficiency (PCE) with 80.59% FF in a ternary D18:PM6:CH1007 system.
• Demonstrated enhanced thermal stability, retaining 91% of PCE after 2000 hours at 85°C.

Conclusions:

• The TRBI strategy effectively suppresses defects at the ZnO/active-layer interface, boosting OSC performance.
• This approach offers a simple and effective route to highly efficient and stable inverted OSCs.
• The universality of the TRBI strategy across different systems highlights its potential for widespread application.