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.
• However, their efficiency is limited by metal oxide transport-layer defects and poor active-layer morphology.
• Conventional devices often lag behind in performance due to these challenges.

Purpose of the Study:

• To develop a strategy to overcome efficiency limitations in inverted OSCs.
• To simultaneously address metal oxide defects and active-layer morphology issues.
• To enhance both the performance and stability of inverted OSCs.

Main Methods:

• A trace-residual buried interface (TRBI) strategy was employed using a thin A-D-A-type acceptor (L8-BO) layer on ZnO.
• This interlayer passivates ZnO surface defects and improves active-layer molecular packing.
• The strategy was tested with various acceptors and photoactive systems, including a D18:PM6:CH1007 ternary system.

Main Results:

• The TRBI strategy significantly improved electron transport and extraction.
• Devices achieved a high power conversion efficiency (PCE) of 18.7% with a fill factor (FF) of 80.59%.
• Markedly enhanced thermal stability was observed, with 91% PCE retention after 2000 hours at 85°C.

Conclusions:

• The TRBI strategy effectively suppresses defects at the ZnO/active-layer contact in inverted OSCs.
• This approach provides a simple and effective route to highly efficient and stable inverted OSCs.
• The universality of the strategy across different systems highlights its broad applicability.