Perovskite based gas sensors: thin-film versus capillary-filled microchannel designs

In the area of environmental monitoring, Volatile Organic Compounds (VOCs) have become a major concern. Specifically, in indoor environments, VOCs have been found to be linked with various health conditions-ranging from benign to lethal. Early detection of VOC gases can play a crucial role in ensuring a safe environment. In this work, we have looked into two different geometrical arrangements of methylammonium lead iodide (MAPbI3) perovskite to study how their selectivity and sensitivity towards an array of VOC gases under different illumination conditions may be affected. For the purpose of a comparative study, we tested the sensitivity of the device using two different photo-resistor designs, namely, (a) capillary-filled microchannels, where microchannels were created on indium tin oxide (ITO) coated plastic substrate, and leveraging the capillary motion force the microchannels were filled with the perovskite precursor solution, and (b) thin-film approach, where perovskite layers were spin coated on substrates with two conductive pads across. Samples of both designs were exposed to four analytes: acetone, ethanol, isopropanol, and methanol. In our previous study on the capillary design, we reported a decrease in photocurrent by about 22% upon exposure to methanol under illuminated conditions. The goal of this comparative study is to identify the viability of the photo-resistor design for fabricating a low-cost and fast-response gas sensor for the purpose of environmental monitoring.