Two-Step Antisolvent Precipitated MAPbI3-Pellet-Based Robust Room-Temperature Ammonia Sensor

Methylammonium lead tri-iodide (MAPbI(3)) hybrid perovskite powder is successfully synthesized using a two-step antisolvent precipitation (TSAP) method. This MAPbI(3) powder is compressed to make a pellet, on the surface of which is designed an ammonia sensor that operates at room temperature. The tetragonal structure and porous morphology with well-connected perovskite grains of the pellet are studied using X-ray diffraction and scanning electron microscopy techniques. This is the first report of air-stable, substrate free, and robust ammonia sensors based on perovskite pellets based in which the perovskite powder is synthesized with an unreported TSAP method. Gas-sensing measurements show responsivity of 200% in 0.3 s and excellent recovery in 3.6 s upon exposure to 10 ppm ammonia gas. The sensor shows excellent structural and morphological ammonia sensing reversibility. A MAPbI(3) pellet stored in ambient air with a relative humidity of 20-45% exhibits a lifetime of 60 d. These results successfully demonstrate new insights for environmentally friendly low-cost manufacturing of highly sensitive robust perovskite ammonia sensors.