Nonhalogenated Solvent-Processed All-Polymer Solar Cells over 7.4% Efficiency from Quinoxaline-Based Polymers

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• All-polymer solar cells (all-PSCs) offer potential for flexible and large-area applications.
• Traditional processing often relies on halogenated solvents, posing environmental and health concerns.
• Developing efficient all-PSCs using environmentally friendly, nonhalogenated solvents is crucial for sustainable technology.

Purpose of the Study:

• To synthesize and evaluate quinoxaline (Qx)-based conjugated polymers as electron donors in all-PSCs.
• To investigate the impact of nonhalogenated solvent processing on the performance of all-PSCs.
• To achieve high power conversion efficiency (PCE) in all-PSCs using green processing methods.

Main Methods:

• Fabrication of all-PSCs using two Qx-based donor polymers (HFQx-T and HFAQx-T) and an acceptor polymer (N2200).
• Processing of the active layer using nonhalogenated tetrahydrofuran (THF) at room temperature, compared to halogenated chloroform (CHCl3).
• Characterization of the active layer morphology, optical properties, and charge transport dynamics.

Main Results:

• Qx-based polymers processed with THF exhibited enhanced absorption coefficients, improved phase separation, and efficient exciton dissociation.
• Charge carrier mobilities were significantly higher when using THF compared to CHCl3.
• The optimized HFAQx-T:N2200 device processed with THF achieved a record power conversion efficiency (PCE) of 7.45% for Qx-based all-PSCs.

Conclusions:

• Nonhalogenated solvent processing, specifically with THF, is highly effective for fabricating high-performance all-PSCs.
• Qx-based polymers are promising materials for efficient and environmentally friendly organic solar cells.
• The achieved PCE of 7.45% represents a significant advancement for all-PSCs processed using green solvents.