Interfacial Engineering of P3HT–SnO2 Quantum Dot Composites for Superior Room-Temperature NH3 Sensing

The development of room-temperature ammonia (NH 3 ) sensors with high sensitivity, selectivity, and stability remains a significant challenge for environmental monitoring and healthcare applications. Herein, an interfacial-engineered P3HT–SnO 2 quantum dot (QD) composite was developed for high-performance room-temperature NH 3 sensing. The composite was fabricated through a facile wet-chemical method, where SnO 2 QDs were uniformly integrated with the p-type P3HT matrix to construct abundant heterointerfaces. The optimized P3HT–SnO 2 QD sensor with a mass ratio of 1:1 exhibited significantly enhanced NH 3 sensing performance, achieving a high response of 188.31% toward 50 ppm NH 3 at room temperature, together with excellent reproducibility, long-term stability, and anti-interference capability. The enhanced sensing behavior is attributed to the formation of p–n heterojunctions between P3HT and SnO 2 QDs, along with the quantum confinement effect of SnO 2 QDs to generate abundant surface-active sites, which induce interfacial charge redistribution, facilitate carrier transport, and promote NH 3 adsorption and surface reactions. Furthermore, density functional theory (DFT) calculations reveal the preferential adsorption of NH 3 molecules on the P3HT–SnO 2 interface, providing theoretical insights into the improved sensing selectivity. This work demonstrates an effective interfacial engineering strategy for constructing high-performance organic–inorganic hybrid NH 3 sensors operating at room temperature.