High-performance room-temperature NO2 sensors based on CH3NH3PbBr3 semiconducting films: Effect of surface capping by alkyl chain on sensor performance

High-performance CH3NH3PbBr3 (MAPbBr(3)) room-temperature NO2 sensors have been developed for the first time based on MAPbBr(3) films prepared directly from perovskite precursor solutions (PSFs) and from surface-capped MAPbBr(3) nanoparticles (NPFs). AFM images of these films revealed that the grain size of MAPbBr(3) crystal in PSFs decreases with the increasing on the concentration of precursor solution, and XRD patterns demonstrate MAPbBr(3) in PSFs packed along with (00l) crystal orientation. However, MAPbBr(3) NPFs have no preferential crystal orientation despite the good crystallinity of MAPbBr(3) NPs. I-V curves revealed different hysteresis loops for these two kinds of films. Sensors with PSF or NPF as semiconducting layer exhibited remarkable and reversible change when they are exposed to NO2 gas. Interestingly, NPF sensors show better sensing performance with a lower detection limit (0.1 ppm) and a larger sensitivity. Experiments also revealed that the selectivity of NPF is better than that of PSF sensors. More importantly, NPF sensors are much more stable than PSF sensors due to the protected surface of perovskite NPs. This study opens a new promising application for organometallic halide perovskite materials, especially for the protected perovskite NPs.