Multimodal Gas Sensor Detecting Hydroxyl Groups with Phase Transition Based on Eco‐Friendly Lead‐Free Metal Halides

Abstract

An electrical and optical responsive chemical-semiconductor gas sensor is developed using Cu(I) halides with a phase transition mechanism. Cu(I) materials exhibit reversible phase transitions between the Cs 3 Cu 2 I 5 and CsCu 2 I 3 with different properties, owing to the formation/destruction of the Cs-I and Cu-Cu bonding when the hydroxyl groups are attached/detached. Among various toxic and atmospheric gases, a Cu(I)-based gas sensor has high selectivity in detecting the hydroxyl group, and the highest sensitivity to water. The reactivity is determined by the polarity, where water with the largest polarity has the strongest attraction for Cu + and I − ions, letting phase transition occur easily. The multimodal sensor red-shifts emission from 445 to 575 nm when it detects hydroxyl gas, and the moisture-sensitive sensor visually confirms response to breaths in less than 5 s and recovery in the air in less than 30 s. The gas sensor can operate at room temperature while applying a constant bias voltage of 1 V, and it also shows excellent sensitivity in a relative humidity range of 15-75%. Furthermore, the sensor maintained ≈90% of its initial responsivity over 1 year.

Reversible tri-state structural transitions of hybrid copper(i) bromides toward tunable multiple emissions

“…Moreover, switching between multiple types of inorganic units leads to changing optical properties that offer new application prospects for copper halides. 29–34 This reversible transformation between two hybrid copper halides under external stimuli was recently reported, demonstrating the potential of solvent-induced phase transition behavior in anti-counterfeiting. 35–37 During this submission, Lei published a reversible single-crystal to single-crystal transition between (ETPP) 2 Cu 4 Br 6 and (ETPP)CuBr 2 very recently.…”

Highly Sensitive H2S Gas Sensor Based on a Lead-Free CsCu2I3 Perovskite Film at Room Temperature

“…Cs–Cu–I perovskite, as a type of lead-free perovskite, has shown excellent properties in the field of photoelectric devices due to being environmentally friendly, its high photoluminescence quantum yield, and its excellent air stability. , Although 1D CsCu 2 I 3 and 0D Cs 3 Cu 2 I 5 have different crystal structures, they exhibited certain gas-sensitive sensing properties, in addition to ultraviolet light detection properties. For instance, Choi et al proposed a novel semiconductor and gasochromic multimodal responsive gas sensor based on the gas-induced phase transition mechanism of Cs 3 Cu 2 I 5 . Sun et al reported nanostructured-network gas sensors based on lead-free CsCu 2 I 3 , which exhibited excellent room-temperature NO 2 sensing properties, including an ultralow limit of detection, excellent repeatability, and good selectivity .…”

“…For instance, Choi et al proposed a novel semiconductor and gasochromic multimodal responsive gas sensor based on the gas-induced phase transition mechanism of Cs 3 Cu 2 I 5 . 33 Sun et al reported nanostructured-network gas sensors based on lead-free CsCu 2 I 3 , which exhibited excellent room-temperature NO 2 sensing properties, including an ultralow limit of detection, excellent repeatability, and good selectivity. 34 However, the detection performance of Cs–Cu–I perovskite materials for other gases has not been reported.…”

Machine Learning-Assisted Sensor Based on CsPbBr3@ZnO Nanocrystals for Identifying Methanol in Mixed Environments

“…In recent years, metal halide perovskite-based gas sensors have become the frontier hotspot in room-temperature-operating gas sensors due to their tunable bandgap, high defect tolerance, low defect density, high carrier concentration, and high carrier mobility . Currently, RT gas sensors based on metal halide perovskites have made great progress. − Nuraini et al have successfully applied a methylammonium lead iodide (MAPbI 3 ) perovskite thin film to an RT volatile organic compound (VOC) gas sensor, including ethanol, methanol, and so on . Chen et al synthesized an RT sensor based on the porous network of CsPbBr 3 , which can detect 1 ppm ethanol and acetone with a sensitivity ( I VOC / I air – 1) of ∼0.03 .…”