Evolved phase separation toward balanced charge transport and high efficiency in polymer solar cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• High-performance polymer solar cells require optimized morphology for efficient charge carrier transport.
• Understanding the relationship between morphology and charge transport is crucial for device development.

Purpose of the Study:

• To synthesize a novel benzodithiophene-based polymer for polymer solar cells.
• To investigate the morphology evolution and charge carrier transport in polymer/fullerene blend films.
• To correlate optimized morphology with enhanced power conversion efficiency.

Main Methods:

• Synthesis of a new benzodithiophene-based polymer.
• Fabrication and characterization of polymer/PC(71)BM blend films.
• Space charge limited current method for charge carrier transport analysis.
• Morphology characterization under varied processing conditions.

Main Results:

• The synthesized polymer exhibits good self-organization and favorable blend film morphology evolution.
• Optimized morphology features nanoscale fibrillar polymer phases with balanced hole and electron mobility (approx. 1:1).
• Achieved a power conversion efficiency of 3.2% under simulated AM 1.5 solar irradiation.

Conclusions:

• Controlled morphology evolution is key to achieving balanced charge carrier transport in polymer/fullerene blends.
• Optimized morphology enhances short-circuit current and reduces recombination losses, boosting solar cell efficiency.
• The developed benzodithiophene-based polymer shows promise for high-performance organic photovoltaic applications.