C60-Terminated Acceptor Boosts Efficiency and Stability in Organic Solar Cells via Interfacial Manipulation

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic solar cells (OSCs) show promise but lag behind silicon photovoltaics in efficiency and stability.
• Non-fullerene acceptors (NFAs) have advanced OSC power conversion efficiency (PCE) to 21%.
• Current NFAs face challenges in miscibility and operational stability, hindering commercialization.

Purpose of the Study:

• To develop a novel A-D-A type non-fullerene electron acceptor with enhanced properties.
• To improve miscibility and interfacial interactions in OSCs for better performance.
• To enhance both the power conversion efficiency (PCE) and operational stability of organic solar cells.

Main Methods:

• Synthesized a new C60-terminated acceptor-donor-acceptor (A-D-A) electron acceptor, C60-L8BO-C60, by replacing indanone end groups with C60 cages.
• Incorporated 5% of C60-L8BO-C60 as a guest component in D18:L8-BO based devices.
• Evaluated device performance, including PCE and exciton dissociation efficiency, and conducted stability tests under harsh conditions (ISOS-L-3).

Main Results:

• C60-L8BO-C60 demonstrated superior miscibility with polymer donors and NFAs compared to PC61BM.
• Devices incorporating C60-L8BO-C60 achieved a maximum PCE of 20.6% (certified 20.25%), with improved exciton dissociation and reduced recombination.
• Operational T80 lifetime was significantly enhanced by 200% (from 270 to 815 hours) under standardized harsh stability testing.

Conclusions:

• The C60-terminated NFA, C60-L8BO-C60, effectively enhances miscibility and interfacial properties in OSCs.
• This novel acceptor material leads to significant improvements in both PCE and operational stability.
• C60-L8BO-C60 shows broad applicability in various polymer:non-fullerene systems, paving the way for commercialization of OSCs.