One-Step Polymerized Stable Open-Shell Poly(3,4-dioxythiophene) Radicals for High Photothermal Conversion and...

Area of Science:

• Materials Science
• Organic Chemistry
• Polymer Science

Background:

• Open-shell organic radical semiconductors offer unique electronic properties but suffer from poor stability.
• Previous work identified diradical character in donor-acceptor semiconductors.
• Sensitivity to oxygen limits the practical application of these materials.

Purpose of the Study:

• To synthesize novel open-shell polymers with improved stability by incorporating oxygen radicals into the polymer backbone.
• To explore a new design strategy for non-doped organic semiconductive radical polymers.
• To evaluate the electronic and photothermal properties of the synthesized materials.

Main Methods:

• One-pot synthesis of three open-shell poly(3,4-dioxythiophene radical) polymers (PTO2-1/2/3) using BBr3 and HBr-mediated oxidation radical polymerization and demethylation.
• Characterization of open-shell character using 1H NMR, electron spin resonance, and MALDI-TOF mass spectrometry.
• Measurement of HOMO energy level, electronic conductivity, and photothermal conversion efficiency under 808 nm laser irradiation.

Main Results:

• Successfully synthesized three novel open-shell poly(3,4-dioxythiophene radical) polymers (PTO2-1/2/3).
• PTO2-2 exhibited a HOMO energy level of -5.42 eV and high electronic conductivity (2.6 × 10^-2 S cm^-1).
• PTO2-2 demonstrated outstanding photothermal conversion, heating from 28°C to 205°C within 60 s under 808 nm laser irradiation.

Conclusions:

• A new design strategy for stable, non-doped, open-shell radical polymers was established.
• The synthesized PTO2 polymers offer a promising platform for applications requiring high electronic conductivity and efficient photothermal conversion.
• This work provides a pathway for constructing low-cost, stable, non-doped open-shell polymers.