Single-Junction Polymer Solar Cells with 16.35% Efficiency Enabled by a Platinum(II) Complexation Strategy.

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Nonfullerene polymer solar cells (NF-PSCs) are promising for renewable energy.
• Achieving high efficiency requires precise control over active layer morphology and molecular packing.
• Polynitrogen heterocyclic polymers like PSFTZ often exhibit strong aggregation, leading to phase separation and suboptimal performance when blended with acceptors like Y6.

Purpose of the Study:

• To develop a novel platinum(II) complexation strategy to improve NF-PSC performance.
• To regulate polymer crystallinity, molecular packing, and blend morphology.
• To enhance the power conversion efficiency (PCE) of NF-PSCs.

Main Methods:

• Synthesis of a s-tetrazine (s-TZ)-containing copolymer, PSFTZ.
• Blending PSFTZ with the nonfullerene acceptor Y6.
• Introducing platinum(II) complex, Pt(Ph)2(DMSO)2, to form complexes with PSFTZ.
• Characterization of the resulting active layer morphology and device performance.

Main Results:

• The pristine PSFTZ:Y6 blend showed a PCE of 13.03% due to significant phase separation.
• Platinum(II) complexation with PSFTZ introduced steric hindrance, reducing polymer aggregation.
• This complexation optimized blend morphology and phase separation, leading to a record PCE of 16.35% for single-junction NF-PSCs.

Conclusions:

• Platinum(II) complexation is an effective strategy for controlling polymer aggregation and blend morphology in NF-PSCs.
• The optimized morphology significantly enhances charge generation and transport, leading to improved device efficiency.
• This work sets a new benchmark for single-junction NF-PSC efficiency.