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

Methylammonium lead bromide (CHNHPbBr) 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 NH gas molecules on the optical properties of CHNHPbBr colloidal QDs. The investigations carried out under a controlled environment reveal that even the presence of 37 ppm of ammonia (NH) gas molecules causes a significant reduction in the PL intensity of CHNHPbBr colloidal QDs. The reduction rate of PL intensity can be tuned with the concentration of NH gas molecules. We propose that the decrease in PL intensity is because of the formation of a non-luminescent NHPbBr phase under the presence of NH gas molecules. Further, the non-luminescent NHPbBr retransformed into luminescent CHNHPbBr on the introduction of methylamine (CHNH) gas molecules. This reversible alternation in PL properties enables us to demonstrate its application for (NH) gas sensing. The advantage of using CHNHPbBr 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.