Textile Based Lead-Free Halide Perovskite CH₃NH₃SnI₃ Ammonia Gas Sensor Working at Room Temperature

We report a textile-based lead-free halide perovskite-based gas sensor to detect ammonia gas at ambient temperature. The sensor uses methylammonium tin iodide (CH3NH3SnI3 or MASnI(3) or MASI) as the active material to grow in fabric substrates using one-step low-temperature (similar to 100 degrees C) solution processing. The as-fabricated textile-based sensor can trace ammonia by both visual color change methods and electrical readout. The maximum calibrated sensitivity based on the electrical readout of the sensor is similar to 85% on exposure to 100 ppm ammonia gas. The sensor can be operated at 2 V bias with an output current of similar to 2 nA, making our device compatible with low-power e-textile-based wearable gas sensors. Further, the gas-sensing performance of the lead-free halide perovskite-based ammonia sensor has been compared with its lead-based counterpart to unify the gas-sensing activity by the family of halide perovskites irrespective of the substitution of cations and anions. The quantitative difference in the sensing activity between lead and lead-free (tin-based) halide perovskites has been complemented by molecular dynamics (MD) simulation.