Dynamic Passivation in Perovskite Quantum Dots for Specific Ammonia Detection at Room Temperature

Abstract

Perovskite structured CsPbX3 (X = Cl, Br, or I) quantum dots (QDs) have attracted considerable interest in the past few years due to their excellent optoelectronic properties. Surface passivation is one of the main pathways to optimize the optoelectrical performance of perovskite QDs, in which the amino group plays an important role for the corresponding interaction between lead and halide. In this work, it is found that ammonia gas could dramatically increase photoluminescence of purified QDs and effectively passivate surface defects of perovskite QDs introduced during purification, which is a reversible process. This phenomenon makes perovskite QDs a kind of ideal candidate for detection of ammonia gas at room temperature. This QD film sensor displays specific recognition behavior toward ammonia gas due to its significant fluorescence enhancement, while depressed luminescence in case of other gases. The sensor, in turn‐on mode, shows a wide detection range from 25 to 350 ppm with a limit of detection as low as 8.85 ppm. Meanwhile, a fast response time of ≈10 s is achieved, and the recovery time is ≈30 s. The fully reversible, high sensitivity and selectivity characteristics make CsPbBr3 QDs ideal active materials for room‐temperature ammonia sensing.

Environment-Induced Reversible Modulation of Optical and Electronic Properties of Lead Halide Perovskites and Possible Applications to Sensor Development: A Review

“…Contrary to results obtained with hybrid perovskites, based sensor works in a PL turn-on mode rather than in a PL quenching one [ 86 ]. The exposition of the sample to ammonia gas reveals an incredible photoluminescence intensity increase of the QDs (about three times than the original one) and the pristine condition is restored when the gas source is removed ( Figure 24 a).…”

“…Contrary to hybrid perovskites, recently it has been demonstrated that fully inorganic perovskite QDs do not suffer from structural modification induced by the interaction with ammonia [ 86 ]. XRD patterns of perovskite before and after exposure have indeed been shown to be quite similar ( Figure 11 c) and measurements on morphology additionally confirm that the size (≃10 nm) and the cubic phase of the quantum dots remain unaltered ( Figure 11 a,b).…”

“…( c ) XRD pattern of QDs before and after treatment. Adapted with permission from [ 86 ]. Copyright © 2020, WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim.…”

“…( b ) Four successive sensing cycles of the QDs at 50 ppm. Adapted with permission from [ 86 ]. Copyright © 2020, WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim.…”

Recent Advances in Flexible Field‐Effect Transistors toward Wearable Sensors

“…[18] Currently, various materials have been fabricated into different kinds of wearable sensors. [19][20][21][22][23][24] In addition to the material applications, reports were also found to use different kinds of electronic devices as the sensing units, [25,26] among which FET-based sensors have drawn the interest of researchers. In addition to the conventional applications of field effect transistors (FETs) in logic circuits as signal amplifiers, etc., FETs play a significant role in sensing devices by fabricating organic/ inorganic semiconductor (OSC) materials into sensor devices with a simple layerby-layer structure [27,28] to improve the sensitivity and stability.…”