A lead-free Cs2PdBr6 perovskite-based humidity sensor for artificial fruit waxing detection

Abstract

Lead halide perovskites recently emerged as promising optoelectronic materials; however the moisture instability and the toxicity of Pb hinder their further application in humidity sensing. Substitution of Pb could help overcome the environmental instability of perovskites. In this paper, an intrinsically moisture-resistant, lead-free perovskite Cs₂PdBr₆ was employed to demonstrate its remarkable humidity sensing performance and utilized for fruit waxing detection for the first time. Cs₂PdBr₆ micro-octahedron is prepared and passivated with oleic acid (OA). The as-fabricated humidity sensors exhibited a response time of 0.7 s and recovery time 1.7 s with an impedance variation range of 10⁵ Ω under relative humidity ranging from 11% to 95%. The artificial waxing on apples and oranges can be discriminated from their surface humidity using the Cs₂PdBr₆-based sensor, indicating more potential applications of these lead-free perovskites.