Reversible luminescent humidity chromism of organic–inorganic hybrid PEA2MnBr4 single crystals

Organic-inorganic hybrids have drawn great attention for gas sensors due to their high sensitivity, good selectivity and acceptable stability at room temperature. There are two main approaches by which organic-inorganic hybrids convert gas information to electric or optical signals (vapochromism). Here, we have reported a new organic-inorganic hybrid PEA2MnBr4 for humidity detection by luminescent visible chromism. PEA2MnBr4 single crystals were grown by the solution method and determined by single-crystal X-ray diffraction. Luminescent humidity chromism was found on PEA2MnBr4 from green emission at the water-desorption state to pink emission at the water-adsorption state within 18 s at a relative humidity of 38% RH. This obviously visible chromism was further used to check the water content in toluene with a low detection limit between 0.02 and 0.05 vol%.