A “Turn-on” fluorescence perovskite sensor based on MAPbBr3/mesoporous TiO2 for NH3 and amine vapor detections

Abstract

Recently, lead halide perovskites have attracted great interest in toxic gas detection, but as gas sensor, it is still a challenge to achieve their high-performance. Here, we propose a novel “turn-on” fluorescence NH3/amine vapor sensor by depositing the CH3NH3PbBr3 (MAPbBr3) on the mesoporous TiO2 (mp-TiO2) layer. The fluorescence intensity of the sensor increases rapidly within seconds upon exposure to NH3 gas (72 % at 5 ppm and 988 % at 100 ppm, respectively) with excellent reversibility, high gas selectivity, humidity insensitivity, and regeneration. Moreover, the sensor can be further used for detecting various amine vapors, including methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, and decylamine. We presumed the “turn-on” fluorescence sensing mechanism is that the trace NH3 or amine molecules could decrease the surface trap defects and facilitate the formation of passivation layer. It will impede the electron-injection into mp-TiO2, which induces the radiative electron-hole recombination and fluorescence enhancement. This research demonstrates that it is feasible to design a “turn-on” fluorescence gas sensor based on the mp-TiO2-based perovskite.