Universal sensing of ammonia gas by family of lead halide perovskites based on paper sensors: Experiment and molecular dynamics.

• Capability of the lead based perovskite halide family towards NH 3 gas sensing both by visual detection as well as electrical detection method. • The compatibility with papers sensor due to low temperature solution processing working at room temperature. • Compatible with extremely low power paper electronics for sensing operation during electrical detection. • The family of lead halide perovskite follows a general sensing mechanism substantiated by molecular dynamics simulation. • Develop them as a common platform for solid state room temperature NH 3 gas sensor with cost effective and disposable, paper based technology. In this paper we show that, high sensitivity and high selectivity room temperature ammonia (NH 3) gas sensors with both visual and electrical response can be made from family of lead halide perovskites with different cations and anions. These sensors, based on papers, act as general platforms for new generation of solid state gas sensors for sensitive detection of NH 3 gas by simple color change (∼10 ppm sensitivity) as well as electrical resistance change with sub ppm sensitivity limited by electrical noise only. The sensors with materials like CH 3 NH 3 PbI 3 (MAPI), CH 3 NH 3 PbBr 3 (MAPB) and CH(NH 2) 2 PbI 3 (FAPI), are grown on paper from solution. MAPB changes color from orange to white and FAPI and MAPI from black to yellow under NH 3 gas exposure respectively. For electrical sensor operation, a fixed concentration (20 ppm) of NH 3 gas, the sensitivity of MAPI is highest at 96 % followed by MAPB at 82 % and FAPI at 65 %. The sensors with electrical read out could trace NH 3 gas well below ppm level with only few nanowatt of power consumption. Based on experiments, a sensing mechanism has been proposed. The proposed mechanism mainly consists of decomposition of the perovskite halides to lead (Pb) halide by preferential adsorption of NH 3 gas molecules. The proposed mechanism has also been substantiated by molecular dynamics simulations. These sensors fabricated by simple solution process on paper substrates and operable at ambient temperature, are compatible with very low power (∼ nW) paper electronics. [ABSTRACT FROM AUTHOR]