Self-Powered, Photovoltaic-Driven NH3 Sensor: Ultra-High Selectivity, High Sensitivity, and IoT-Enabled Real-Time Monitoring with Novel Organic Molecule Functionalized TiZnN2/p-Si Heterostructure

Ammonia (NH3) detection is vital for environmental monitoring, industrial safety, and food quality assurance. Conventional sensors based on metal oxides, conducting polymers, and 2D materials often require external power, limiting their efficiency. Here, a novel self-powered NH3 sensor utilizing silicon corrole-functionalized TiZnN2 (SipC-TiZnN)/p-Si heterostructure is presented. By integrating the photovoltaic effect of the TiZnN2/p-Si junction with gas sensing, the device enables efficient charge separation under visible light without external power. It demonstrates outstanding NH3 sensitivity (2.62 x 10(-)(4) ppm(-)(1)) and an ultra-low detection limit of 0.9 ppm. The sensor exhibits a superior selectivity for NH3 over other gases, maintains stability for over 90 days, and operates reliably in humid conditions (approximate to 75% RH). Mechanistic insights from Density Functional Theory calculations and Scanning Kelvin Probe measurements confirm strong NH3 adsorption. A portable, IoT-enabled prototype validates real-time NH3 monitoring for fish freshness assessment, highlighting its potential for environmental, food safety, and industrial applications. This work represents a significant advancement in energy-efficient sensing, bridging the gap between high-performance materials and real-world deployment.