Detecting alcohol vapors using two-dimensional copper-based Ruddlesden–Popper perovskites

The detection of alcohol vapors has many important applications, such as measuring the breath ethanol content to prevent drug-impaired driving. A medical application is the detection of 1-propanol because this compound was found to be a potential marker for lung cancer screening. This work reports an alcohol sensor using the two-dimensional Ruddlesden–Popper perovskite bis(phenethylammonium) tetrachlorocuprate—(PEA)2CuCl4, also known as phenethylammonium copper chloride—as the sensing material. The device is based on a change in conductance upon exposure to alcohol vapors. A comparison between pristine (PEA)2CuCl4 and (PEA)2CuCl4 after a treatment with ultraviolet light shows that the latter has a higher conductance. Devices made with this UV-converted material show a strong response to 1-propanol vapors, starting from a concentration around 2000 parts per million (ppm). Additionally, these devices demonstrate stable behavior in a nitrogen atmosphere. During the stabilization of the 1-propanol flow rate, the concentration fluctuates. These fluctuations were detected by monitoring the current of the device over time, down to steps in 100 ppm around a concentration of 8000 ppm. The conductance of the devices decreases in contact with air. However, this process can be reversed by additional ultraviolet illumination, thereby making the devices reusable.