Synthesis, Characterization and Performance of P3HT-Azide-PCBM Microgel

Area of Science:

• Materials Science
• Polymer Chemistry
• Organic Electronics

Background:

• Conjugated polymers like Poly(3-hexylthiophene) (P3HT) are crucial for organic electronics.
• Developing stable and processable forms of these materials is essential for device fabrication.
• Incorporating cross-linkable groups can enhance material stability and morphology control.

Purpose of the Study:

• To synthesize a spherical microgel of P3HT-azide-PCBM for potential use in bulk-heterojunction (BHJ) devices.
• To investigate the structural, optical, and morphological properties of the synthesized microgel.
• To evaluate the impact of the microgel on the performance of BHJ photovoltaic devices.

Main Methods:

• Synthesis of P3HT-azide-PCBM microgel via azide cross-linking.
• UV-vis and fluorescence spectroscopy for optical characterization.
• Gel Permeation Chromatography (GPC), Dynamic Light Scattering (DLS), and Static Light Scattering (SLS) for size and uniformity analysis.
• Fabrication and testing of BHJ devices incorporating the microgel.

Main Results:

• Successful synthesis of uniform spherical P3HT-azide-PCBM microgels with a hydrodynamic radius of 130 nm.
• UV-vis spectra showed blue shifts, indicating disrupted planarity and reduced conjugation in P3HT.
• Fluorescence spectra revealed intramolecular photo-induced electron transfer due to PCBM covalent linkage.
• BHJ devices with the microgel exhibited reduced photovoltaic performance compared to P3HT/PCBM blends.

Conclusions:

• The synthesized P3HT-azide-PCBM microgel offers potential as an electron donor or compatibilizer in BHJ devices.
• The cross-linking process and microgel formation negatively impacted hole mobility within the polythiophene backbone.
• Further optimization is needed to improve photovoltaic performance when using this cross-linked microgel system.