Fully Inorganic Metal Halide Perovskite CsGeBr₃ Photoferroelectrics for Room-Temperature Photovoltaic Self-Powered Ammonia Detection

Chemiresistive sensing technology plays a significant role in the field of gas monitoring. However, conventional metal oxide gas monitoring devices typically require high operating temperatures and external power supplies to power them. In this paper, we have exploited the property that the photoferroelectric material CsGeBr₃ can provide a stable output source through a self-polarization field under light illumination to achieve a good self-powered gas sensing response to NH₃ at room temperature, including extremely fast response/recovery time (30 s/40 s), and low concentration sensing (response value of 2.02 at 50 ppm of NH₃). This demonstrates significant advantages and a wider range of application scenarios than those of conventional metal oxide gas sensors that require an external power supply. Fourier transform infrared (FTIR) spectroscopic measurements confirmed the high selectivity of CsGeBr₃ for NH₃, which to our knowledge is the first time that Ge-based all-inorganic photoferroelectric materials of perovskite have been applied to the field of self-powered gas sensing, and the present work provides a new material and direction in the study of self-powered gas sensors.