Highly conductive polythiophene films doped with chloroauric acid for dual-mode sensing of volatile organic amines and thiols

• P3HT films with high electrical conductivity were facilely prepared by HAuCl4 doping.
• The HAuCl4-doped P3HT film could be easily dedoped by volatile amines and thiols vapors.
• Associated color and conductivity variation of P3HT during dedoping was significant.
• Sensitive logic gates for selectively sensing of amines and thiols using HAuCl4-doped P3HT.

Highly conductive polythiophene films with electrical conductivity of 71.7 S/cm were prepared by using a facile solution-processing method with HAuCl4 as a dopant. The density of free charge carriers for thus-prepared polythiophene films was estimated to be 4.48 × 1021/cm3. In addition, upon doping, the color of the polymer films changed significantly with the main absorption peaks bathochromically shifted from the visible to near-infrared region. Interestingly, the polythiophene films could be easily dedoped when exposed to organic amines and thiols. The dual variations of film color and electrical conductivity thus were exploited for the design and fabrication of a logic circuit, in combination with polythiophene films doped by electrochemical oxidation, for selective detection of volatile amines and thiols with a detection limit lower than 1 ppm. The results demonstrate the high potential of this solution-doping method in the preparation of highly conducting organic thin films for vapor sensing.

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