Bromine-defect induced high sensitivity of Cs4PbBr6 nanocrystals humidity sensor

Recently, all-inorganic halide perovskite materials have attracted much attention in the fields of humidity sensor due to their sensitive surface, tunable bandgap, high conductivity and excellent carrier mobility. However, their inherent instability and limited sensitivity restrict further application in electronic devices. Herein, we demonstrate a high-performance impedimetric humidity sensor based on an all-inorganic halide perovskite Cs 4 PbBr 6 nanocrystals (NCs), which are obtained by anti-solvent method without long chain ligands. It is found that V Br ∙ defects act as the active site to enhance the ability of adsorbing water molecules. The humidity sensor of Cs 4 PbBr 6 NCs achieves high response value over 4 orders of magnitude at 11–98 % relative humidity, short response/recovery time (8 s/6 s), favorable repeatability, excellent selectivity and good long-term stability. Moreover, high humidity sensing performance enables the humidity sensor of Cs 4 PbBr 6 NCs to possess great potentials in breath monitor and noncontact switch application.