Narrow-Bandgap Single-Component Polymer Solar Cells with Approaching 9% Efficiency.

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Single-component organic solar cells (SCOSCs) offer simplified device fabrication.
• Developing efficient and stable materials for SCOSCs remains a key challenge.
• Narrow bandgap polymers are crucial for broad light absorption.

Purpose of the Study:

• To design and synthesize novel narrow-bandgap block conjugated polymers for SCOSCs.
• To investigate the structure-property relationships of these polymers.
• To enhance the power conversion efficiency (PCE) and stability of SCOSCs.

Main Methods:

• Synthesis of two block conjugated polymers: PBDB-T-b-PIDIC2T and PBDB-T-b-PTY6.
• Fabrication and characterization of single-component organic solar cells (SCOSCs).
• Analysis of charge carrier dynamics, film morphology, and device stability.

Main Results:

• Achieved a record power conversion efficiency (PCE) of 8.64% in SCOSCs.
• Demonstrated significantly improved short-circuit current density (Jsc) over 15 mA cm⁻².
• Exhibited low energy loss (high charge transfer states and small non-radiative loss) and excellent stability (>1000 h at 80 °C).

Conclusions:

• The synthesized narrow-bandgap block polymers are promising candidates for high-performance SCOSCs.
• Reduced ordering in block copolymers contributes to increased carrier recombination.
• This work provides a framework for further molecular design to boost SCOSC efficiency.