Tailoring Nanoscale Morphology of Polymer:Fullerene Blends Using Electrostatic Field

Area of Science:

• Materials Science
• Organic Electronics
• Nanotechnology

Background:

• Polymer/fullerene blends are crucial for organic photovoltaics (OPVs).
• Controlling nanomorphology is key to optimizing OPV performance.
• Existing methods for morphology control have limitations.

Purpose of the Study:

• To investigate the effect of electrostatic fields (E-fields) on the solidification of P3HT:PC60BM bulk heterojunctions.
• To tailor the nanomorphology of polymer/fullerene blends for improved device performance.
• To establish E-field treatment as a novel morphology-tuning technique.

Main Methods:

• Thin films of poly(3-hexylthiophene-2, 5-diyl) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC60BM) were treated with an electrostatic field from a Van de Graaff generator.
• E-field treatment was applied in horizontal, tilted, and vertical directions relative to the substrate.
• Surface and bulk characterizations were performed on treated and control samples.

Main Results:

• Fullerene molecules (PC60BM) were observed to penetrate the polymer matrix (P3HT) and move along the E-field lines.
• Favorable morphologies were achieved, leading to efficient charge separation, transport, and collection.
• Hole mobility improved up to 19.4 × 10^-4 cm^2 V^-1 s^-1.
• Power conversion efficiency (PCE) reached 2.58% for conventional OPVs and 4.1% for inverted OPVs.

Conclusions:

• E-field treatment effectively controls nanomorphology in P3HT:PC60BM blends.
• This method enhances charge carrier mobility and device efficiency in OPVs.
• The E-field approach is a versatile technique applicable to other polymer-fullerene systems.