Fast Lead-Free Humidity Sensor Based on Hybrid Halide Perovskite

Abstract

An environmentally friendly analog of the prominent methylammonium lead halide perovskite, methylammonium bismuth bromide (MA3Bi2Br9), was prepared and investigated in the form of powder, single crystals and nanowires. Complete characterization via synchrotron X-ray diffraction data showed that the bulk crystal does not incorporate water into the structure. At the same time, water is absorbed on the surface of the crystal, and this modification leads to the changes in the resistivity of the material, thus making MA3Bi2Br9 an excellent candidate for use as a humidity sensor. The novel sensor was prepared from powder-pressed pellets with attached carbon electrodes and was characterized by being able to detect relative humidity over the full range (0.7–96% RH) at ambient temperature. Compared to commercial and literature values, the response and recovery times are very fast (down to 1.5 s/1.5 s).

Thermochromism in Bismuth Halide Perovskites with Cation and Anion Transmutation

“…This compression leads to an increased overlap between the Bi 6s/6p and Br 4p states, resulting in a smaller bandgap. [ 14f,15a,17b,18 ] After Ag incorporation in Cs 3 Bi 2 Br 9 , the absorption edge of Cs 2 AgBiBr 6 is significantly shifted toward higher wavelengths, indicating the reduction in the optical bandgap. The involvement of Ag atom orbitals has contributed to the band edges of Cs 2 AgBiBr 6 , thereby increasing the electronic dimensionality compared to the original Cs 3 Bi 2 Br 9 .…”

Band-gap engineering in methylammonium bismuth bromide perovskites for less-toxic perovskite solar cells

“…A study by Djokic et al produced a more expected MA 3 Bi 2 Br 9 material, with 2D layered structure belonging to the space group P% 3m1, similar to previous studies on bismuth and antimony halide perovskites. 43,44 It is also unlike the crystal structure of methylammonium bismuth iodide, which usually possesses a structure in which two face-sharing octahedra form the main part of the repeating unit. 45 This difference is likely due to the synthesis method of the single crystals, a slow, solvent evaporation-based method that allows plenty of time for the crystallisation of the material to include the DMSO solvent.…”

“…Other solvents to DMSO should be explored, as the formation of the DMSO solvate crystal into a zero-dimensional structure, as opposed to the previously reported 3-D crystal structures, likely hampers performance. 43,44…”

Hybrid 1D/3D-Structured Perovskite as a Highly Selective and Stable Sensor for NO2 Detection at Room Temperature

“…[ 10 , 11 , 12 , 13 ]. More interestingly, in recent years, perovskites have begun to rise as a promising sensor material in detecting NO 2 , oxygen, ozone, ammonia, sulfur dioxide, humidity, organic vapors [ 9 , 14 , 15 , 16 , 17 , 18 , 19 ], etc. For instance, Fang et al in 2016 demonstrated that methylammonium lead tribromide (MAPbBr 3 ) single crystal showed an ultrahigh sensitivity toward the environmental atmosphere, including oxygen and water vapor [ 16 ].…”