摘要
•A Room temperature ammonia gas sensor using DIC-TRZ is demonstrated.•The ammonia detection range presented in this work is 100 to 2000 ppb.•The operation current of the DIC-TRZ sensor is stable.•With F4-TCNQ dopant, the operation current of the sensor is increased to 25-fold.•The real-time current reading of the sensor can be implemented by a low-cost multimeter.
The detection and monitoring of ammonia (NH₃) gas are critical for various applications, including environmental monitoring, industrial safety, and medical diagnostics. NH₃ is a significant biomarker for chronic kidney disease and the effectiveness of hemodialysis, requiring sensors capable of detecting ppb-level concentrations. While advanced analytical techniques meet the sensitivity requirements, their high cost and complex instrumentation limit practical applications. Developing cost-effective, highly sensitive, and user-friendly ammonia sensors remains a priority.
This study presents a room-temperature NH₃ gas sensor based on 2,4-diphenyl-6-bis(12-phenylindolo)[2,3-a]carbazole-11-yl)-1,3,5-triazine (DIC-TRZ), a material known for its high carrier mobility and stable electrical properties. The sensor was integrated into a vertical nano-junction device structure, and its performance was enhanced using a p-type doping strategy with 1 wt % F4-TCNQ. The operational current, sensitivity, limit of detection (LOD), stability, and selectivity were systematically evaluated.
The DIC-TRZ-based sensor demonstrated excellent ammonia detection performance, with a sensitivity of 0.0467 %/ppb and an LOD of 20.7 ppb for the non-doped device, and a sensitivity of 0.0391 %/ppb and an LOD of 16.0 ppb for the doped device. The sensor exhibited rapid response and recovery times and a stable operational current. The doping strategy increased the current by nearly two orders of magnitude, reaching ∼10⁻⁵ A, significantly improving the signal-to-noise ratio. This enhancement enabled real-time current measurement using a low-cost multimeter, broadening the applicability for environmental monitoring, medical diagnostics, and portable applications.
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