A TPA-DCPP organic semiconductor film-based room temperature NH3 sensor for insight into the sensing properties

Ammonia (NH3) gas sensor is an indispensable element in human daily life, especially in the respiratory analysis, it can perform non-invasive diagnosis of kidney disorder and hepatitis. Addressing the issue of high working temperature and achieving repeatable and stable gas-sensing properties under ambient humidity is favorable for the widespread development of NH3 sensor. In this work, a planar room-temperature NH3 sensor is manufactured through spin-coated 7,10-bis(4-(diphenylamino)phenyl)-2,3-dicyanopyrazino phenanthrene (TPA-DCPP) organic semiconductor material onto Al2O3 substrate with Au interdigital electrodes. The sensor exhibits favorable sensing response of 76.4 % and ppb-level detection ability under 98 % relative humidity (RH), also exhibits good repeatability, selectivity, and 396 days of long-term stability to NH3. The sum frequency generation (SFG)/density functional theory (DFT) calculation results further demonstrate that the excellent sensing characteristics are due to the enhanced NH3 absorption to TPA-DCPP through the synergy interaction between NH3 and H2O under high RH. This study is expected to serve as a reference in the further development of room-temperature gas sensors and contribute to our understanding of the sensing mechanism.