Efficient polymer solar cells based on a low bandgap semi-crystalline DPP polymer-PCBM blends

Area of Science:

• Materials Science
• Polymer Chemistry
• Organic Electronics

Background:

• Diketopyrrolopyrrole-based polymers are promising for organic solar cells due to their tunable low bandgaps.
• Controlling polymer morphology is crucial for efficient charge transport and device performance.
• Understanding the self-assembly and aggregation behavior of these polymers is key to optimizing their use.

Purpose of the Study:

• To characterize the performance and morphology of a novel diketopyrrolopyrrole-based low bandgap polymer.
• To investigate the effect of solvent mixture processing on polymer morphology.
• To elucidate the morphology development mechanism during film formation.

Main Methods:

• Solar cell fabrication and performance testing.
• Grazing-incidence X-ray diffraction (GIXD) for structural analysis.
• Grazing-incidence small-angle X-ray scattering (GISAXS) for morphology investigation.

Main Results:

• The polymer exhibits H-type aggregation, which is beneficial for charge transport.
• Solvent mixture processing resulted in improved film morphology compared to single solvents.
• A four-step mechanism describing the morphology evolution was proposed based on GIXD and GISAXS data.

Conclusions:

• The studied diketopyrrolopyrrole-based polymer shows potential for organic solar cell applications.
• Optimized processing using solvent mixtures can enhance morphology and device performance.
• The proposed morphology development mechanism provides insights for designing high-performance organic electronic materials.