Halide-dependent humidity sensing of Cs 2 SnX 6 (X = Cl, Br, I) perovskites for real-time human physiological moisture detection

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2024
• Main Authors: Guo, Chen-Chen, Wang, Chao-Jie, Zhang, Le-Xi, Qiu, Qi-Da, Zhu, Meng-Ya, Yin, Jing, Bie, Li-Jian
• Format: Article
• Language: English
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/D4TC01463D

Halide perovskites (HPs) have received increasing attention in the last two decades due to unique component diversity and structural tunability, although additional efforts are necessary for HPs beyond photovoltaic and light-emitting domains, e.g. gas/humidity sensing. Here, all-inorganic lead-free HPs Cs 2 SnX 6 (X = Cl, Br, I) were synthesized by simple room-temperature precipitation without any surfactant or organic solution. Afterwards, Cs 2 SnX 6 HPs were systematically investigated in terms of structure, morphology, energy band and surface state. Explored as humidity sensing materials, Cs 2 SnX 6 exhibit favorable humidity sensing performance with a response sequence of Cs 2 SnCl 6 > Cs 2 SnBr 6 > Cs 2 SnI 6 . Remarkably, the Cs 2 SnCl 6 sensor achieves a long-term stability at 11–97% relative humidity (RH) and a high response value of 4 orders of magnitude (3.6 × 10 4 ) with a short response time (15 s). Furthermore, the precise humidity detection capability makes the Cs 2 SnCl 6 sensor extremely promising for real-time, non-contact human breath and finger monitoring. Ultimately, complex impedance spectra at various RH levels provide an explanation for the humidity sensing mechanism. In addition to offering an optional material for humidity sensors, this work offers fresh perspectives on next-generation sensory devices that use lead-free HPs to detect physiological aspects of human health.