Probing reversible photoluminescence alteration in CH3NH3PbBr3 colloidal quantum dots for luminescence-based gas sensing application

Methylammonium lead bromide (CH3NH3PbBr3) colloidal quantum dots (QDs) exhibit strong green photoluminescence (PL) with high photoluminescence quantum yield (PLQY) making it valuable for various optoelectronic applications. Under the influence of polar gaseous molecules, hybrid halide perovskites show changes in its structural and electrical properties. We, for the first time, have investigated the influence of NH3 gas molecules on the optical properties of CH3NH3PbBr3 colloidal QDs. The investigations carried out under a controlled environment reveal that even the presence of 37 ppm of ammonia (NH3) gas molecules causes a significant reduction in the PL intensity of CH3NH3PbBr3 colloidal QDs. The reduction rate of PL intensity can be tuned with the concentration of NH3 gas molecules. We propose that the decrease in PL intensity is because of the formation of a non-luminescent NH4PbBr3 phase under the presence of NH3 gas molecules. Further, the non-luminescent NH4PbBr3 retransformed into luminescent CH3NH3PbBr3 on the introduction of methylamine (CH3NH2) gas molecules. This reversible alternation in PL properties enables us to demonstrate its application for (NH3) gas sensing. The advantage of using CH3NH3PbBr3 colloidal QDs for luminescence-based sensing is that its green emission is visible with the naked eye even under daylight, which is easy to detect.