Enabling over 20% Efficiency Organic Solar Cells by Molecular Configuration Modulation of Naphthalene Diimide-Based...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Cathode interlayers (CILs) are crucial for high power conversion efficiency (PCE) in organic solar cells (OSCs).
• Tuning CIL molecular structure significantly impacts device performance.

Purpose of the Study:

• To design and synthesize novel D-A type CILs with varying bridging structures.
• To investigate the structure-property-performance relationships of these CILs in OSCs.

Main Methods:

• Synthesis of three D-A type CILs (NDIT1, NDI1, NDIT2) via conjugated core extension and molecular configuration regulation.
• Fabrication and characterization of OSC devices utilizing the synthesized CILs.
• Systematic investigation of the influence of CIL molecular structure on OSC performance.

Main Results:

• The NDIT2 CIL, featuring a rigid fused ring bridge, exhibited enhanced planarity, crystallinity, and self-doping.
• NDIT2 facilitated highly ordered molecular assembly, leading to uniform interfaces, efficient charge transport, and suppressed recombination.
• OSCs with NDIT2 achieved a champion PCE of 20.03%, surpassing those with NDIT1 (18.95%) and NDI1 (19.16%), with excellent initial operational stability.

Conclusions:

• Molecular configuration and conjugation synergistically modulate CIL performance.
• Rational design of CILs through precise structural optimization is key to high-performance organic solar cells.
• The developed strategy offers an effective route for designing advanced cathode materials for OSCs.