Synthesis and Characterization of MAPI:ZnS Color Change Detection by Ammonia Gas at Room Temperature

The research demonstrates that perovskite methylammonium lead iodide (MAPI) can detect various hazardous and polluting chemicals, including ammonia gas (NH3), in the environment. To enhance the sensitivity and response time and modify the structural properties of pure MAPI, zinc sulfide (ZnS) is incorporated in three different concentrations (1, 2.5, and 5 wt%). The sensitivity of these ZnS-doped samples is evaluated for detecting NH3 and alcohol vapor. Sensors based on MAPI:ZnS composites are fabricated on writing paper samples using a solution-processing technique. Upon exposure to NH3, MAPI undergoes a colorimetric change from black to yellow. This phenomenon is attributed to the degradation of perovskite (MAPI) halides into lead (Pb) halides through the preferential adsorption of NH3 molecules. The structural properties were analyzed using X-ray diffraction (XRD) patterns, which revealed a slight shift in the diffraction peaks towards higher 2θ angles. Field Emission Scanning Electron Microscopy (FESEM) images displayed rod-like morphologies, with an average diameter of approximately 49 nm for pure MAPI and around 46 nm for the ZnS-doped samples.