Perovskite nanomaterials as optical and electrochemical sensors

The perovskite family is comprised of a great number of members because of the possible flexible substitution of numerous ions in its system. These compounds have a broad range of applications due to their outstanding optoelectronic properties in solar cells, photodetectors, lasers, and light-emitting diodes (LEDs). Perovskite nanocrystals (PNCs) are highly tolerant to defects, unlike metal chalcogenides, and do not require surface passivation to retain high quantum yields. Interestingly, the defect structures and trap states in perovskites are often found only in their conduction and/or valence bands and not in the mid-states of the bandgap. Such characteristics essentially boost their properties and largely favor their sensing applications. Perovskites have thus been attempted by numerous groups to address the serious concern of heavy metal ions, biomolecules, and gas molecule detection with high selectivity and sensitivity limits. In this context, the current review describes recent developments and various strategies used in applying perovskites as probes for sensing various contaminants, drugs, and gases in the environment. The focus is on two main aspects: (i) the exploitation of the high fluorescence of these perovskites for optical sensing and (ii) the utilization of the redox ability of these perovskites for electrochemical sensing. This review also outlines the existing challenges, giving future perspectives for developing perovskite-based sensing probes of high sensitivity and enduring stability for a range of environmental analytes.