Ternary Organic Solar Cells Based on Two Compatible Nonfullerene Acceptors with Power Conversion Efficiency >10

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic solar cells (OSCs) offer a promising alternative to conventional silicon-based photovoltaics due to their flexibility and low manufacturing costs.
• Ternary blends, incorporating a third component, have emerged as a strategy to enhance OSC performance by optimizing morphology and charge transport.
• Nonfullerene acceptors (NFAs) have shown significant potential in achieving high power conversion efficiencies in OSCs.

Purpose of the Study:

• To investigate the fabrication of ternary organic solar cells (OSCs) using two distinct nonfullerene acceptors (NFAs) and a copolymer.
• To understand the morphological and electronic interactions between the NFAs and the copolymer in the active layer.
• To achieve high power conversion efficiencies in OSCs through optimized ternary blend composition.

Main Methods:

• Fabrication of ternary organic solar cells (OSCs) using a specific copolymer and two different nonfullerene acceptors (NFAs).
• Characterization of the blend film morphology, including crystallinity and phase separation, using techniques like X-ray diffraction and microscopy.
• Performance evaluation of the fabricated OSCs through current density-voltage (J-V) measurements and external quantum efficiency (EQE) analysis.

Main Results:

• The two NFAs exhibited unique interactions within the blend film, leading to reduced crystallinity.
• A homogeneous mixed phase was formed in the blend film, facilitating efficient charge transport and minimizing recombination.
• The ternary OSCs achieved a high power conversion efficiency (PCE) of approximately 10.3%.
• This efficiency represents the highest performance reported to date for nonfullerene ternary blends.

Conclusions:

• The strategic combination of two NFAs and a copolymer enables the formation of an optimal morphology for high-performance OSCs.
• The observed unique interactions between NFAs are crucial for achieving reduced crystallinity and a homogeneous active layer.
• This study presents a novel and effective approach for fabricating high-efficiency ternary organic solar cells, paving the way for future advancements in organic photovoltaics.