Poly3‐Hexylthiophene Titanium Dioxide (P3HT‐TiO₂) Composite Sensor for High Response Detection of Ammonia at Room Temperature

Abstract Gas sensors for ammonia (NH₃) play a crucial role in the maintenance of air quality, preservation of the atmosphere, and evaluation of human health. However, the endeavor to attain a high level of sensitivity in detecting NH₃ under ambient conditions remains a challenging task. In this work, poly(3‐hexylthiophene)s and titanium dioxide (P3HT‐TiO₂) heterostructure NH₃ gas‐sensitive material was prepared, and by drop‐casting the material onto a substrate with Au interdigital electrodes, a sensor for high‐response detection of NH₃ at room temperature was constructed. The designed gas sensor exhibited a high response signal of 114.61 % toward 15 ppm NH₃ at room temperature (25 °C) with good reproducibility, strong long‐term stability, and excellent selectivity. Moreover, by analyzing the response law of the sensor under different humidity conditions, it has been noted that both excessively high and excessively low levels of humidity adversely affect the sensor's response. The remarkable increase in NH₃ sensing properties is attributed to the synergistic enhancement effect of P−N heterojunction formed between P3HT and TiO₂. This NH₃ gas sensor exhibits tremendous potential for use due to its straightforward structure and outstanding ammonia sensing performance.