A Fused-Ring Electron Acceptor with Phthalimide-Based Ending Groups for Efficient Ternary Organic Solar Cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Ternary strategy is a proven method for enhancing organic photovoltaics (OPVs) performance.
• Traditional electron acceptors in OPVs often utilize specific ending groups that can be modified.

Purpose of the Study:

• To design and synthesize a novel fused-ring electron acceptor, BTP-PIO, with modified phthalimide-based ending groups.
• To investigate the performance of a ternary organic solar cell device incorporating BTP-PIO as a guest electron acceptor.
• To explore the impact of ending group modification on the properties and efficiency of OPV materials.

Main Methods:

• Synthesis of the novel electron acceptor BTP-PIO.
• Fabrication and characterization of ternary organic solar cell devices (PM6:Y6:BTP-PIO).
• Performance evaluation including open-circuit voltage (VOC), short-circuit current density (JSC), fill factor (FF), and power conversion efficiency (PCE).
• Analysis of charge transfer, carrier recombination, energy loss, miscibility, and molecular packing.

Main Results:

• BTP-PIO exhibits a higher lowest unoccupied molecular orbital (LUMO) level and wider band gap compared to Y6.
• The ternary device achieved a power conversion efficiency (PCE) of 17.10%, outperforming the binary device (16.08%).
• The ternary device demonstrated improved charge transfer, reduced carrier recombination, and lower energy loss.
• BTP-PIO showed good miscibility with Y6, forming an alloy phase that improved phase separation and molecular packing.

Conclusions:

• Ending group modification of Y6 derivatives is an effective strategy for developing highly efficient ternary organic solar cells.
• The phthalimide-based ending groups in BTP-PIO contribute to enhanced device performance.
• Ternary devices incorporating BTP-PIO offer a promising route to overcome limitations in binary OPV systems.