An Intrinsically Conductive Cross-Conjugated Polymer with a Quinhydrone-Like Donor-Acceptor Charge-Transfer Network

Area of Science:

• Materials Science
• Polymer Chemistry
• Organic Electronics

Background:

• Intrinsically conductive polymers (ICPs) are crucial for stable electronics but are often limited by unstable dopants.
• Developing dopant-free ICPs with reliable performance remains a significant synthetic challenge.

Purpose of the Study:

• To synthesize and characterize a novel dopant-free intrinsically conductive polymer.
• To explore the potential of polymeric charge-transfer complexes for advanced electronic applications.

Main Methods:

• A three-step synthesis route for poly(3,4-dihydroxythiophene-alt-thiophene-3,4-dione) (HOT-DOT).
• Air oxidation to create a balanced 1:1 donor-acceptor architecture.
• Spectroscopic and computational analyses to understand charge transport mechanisms.

Main Results:

• HOT-DOT exhibits intrinsic conductivity (∼0.29 S cm^-1) with a narrow bandgap (1.38 eV) and broad NIR absorption.
• Achieved an ultrasmall π-π stacking distance (3.25 Å) due to strong interchain donor-acceptor interactions.
• Demonstrated positive temperature coefficient (PTC) behavior, long-term ambient stability, and reproducible sensor performance.

Conclusions:

• Polymeric charge-transfer complexes offer a new design strategy for dopant-free intrinsically conductive polymers.
• HOT-DOT shows potential for applications in flexible electronics, particularly in temperature sensing.
• The self-doped nature and stability of HOT-DOT open avenues for reliable electronic devices.