Anomalous NH₃-Induced Resistance Enhancement in Halide Perovskite MAPbI₃ Film and Gas Sensing Performance

Abstract

Despite the growing interest in halide perovskite-based NH3 sensors, the NH3 sensing mechanism is still not well understood. Here, we report an anomalous behavior of resistance enhancement in CH3NH3PbI3(MAPbI3) perovskite films upon exposure to NH3 gas, which is contrary to a resistance drop trend in previously reported perovskites. We propose a NH3 sensing mechanism in which the anomalous resistance enhancement is dominated by grain boundaries of perovskites. It is demonstrated that NH3 molecules can substitute MA+ cations of MAPbI3 to form the insulating NH4PbI3·MA intermediate layers onto the surface of crystal grains, thereby resulting in an increase of resistance. Additionally, we construct the MAPbI3-based sensor, and achieve a gas response of 472% toward 30 ppm of NH3. This study suggests the potential of the perovskite-based NH3 sensors, and also provides guidance for developing high-performance sensing perovskite materials.

Recent Progress of Halide Perovskites Applied to Five Senses Sensors

“…Phase changes of perovskites result in significant differences in their electrical properties, resulting in a response of 472% at 30 ppm of NH 3 . 77 The NH 3 gas detection mechanism remains unclear; however, numerous studies have proposed perovskite-based NH 3 sensors. Casanova-Chafer et al fabricated a sensor with graphene and MAPbI 3 .…”

A review on the sensing mechanisms and recent developments on metal halide-based perovskite gas sensors

“…202 Li et al showed an anomalous behavior of resistance enhancement dominated by the grain boundaries in MAPbI 3 perovskite films upon exposure to NH 3 gas. 203 This occurs mainly due to the substitution of MA + cations by NH 3 molecules and the formation of insulating NH 4 PbI 3 ÁMA intermediate layers on the surface of the crystal grains. The sensor showed a gas response of 472% toward 30 ppm of NH 3 at room temperature.…”

“…158 The performance of gas sensors based on different metal halide perovskites is summarized in Table 1. 14,33,36,37,142,143,149,151,158–208…”

Carbon monoxide induced self-doping in methylammonium lead iodide films and associated long-term degradation effects

“…[18][19][20] However, the effect of gases that are present in a limited concentration in the atmosphere and many controlled conditions, can be detrimental owing to their strong interaction with MAPbI 3 . 21,22 Limited research has been conducted in this area which can provide critical insights into increasing the stability and performance of the perovskitebased devices. 23,24 In this work, we show through the use of a variety of gases that carbon monoxide (CO) has strong interaction with MAPbI 3 .…”