Calcium Titanate Orthorhombic Perovskite-Nickel Oxide Solar-Blind UVC Photodetectors with Unprecedented Long-Term Stability Exceeding 500 Days and Their Applications to Real-Time Flame Detection

In recent years, the rapid increase in fire frequency has led to demands for efficient fire monitoring systems. To realize sensitive and large-area fire monitoring, flame sensing based on an ultraviolet C (UVC) photodetector can be considered as a promising approach. However, the challenges such as the high-cost process, limited selection of photoactive materials with an appropriate band gap, inefficient power consumption, stability issues, and environmental noise interference restrict the development of UVC photodetectors (PDs) for practical flame safeguard applications. Here, we demonstrate flame detection with a UVC PD based on an ultrawide band gap calcium titanate (CTO) and nickel oxide (NiO) heterostructure. The proposed PD achieves a high solar-blinded rejection ratio (at UVC light/UVA light) of 2.9 × 104, on/off switching current ratio of 120 A/A under UVC light and dark state, robust and stable operation longer than 1 year (502 days), and specific detectivity as high as 4.44 × 1011 Jones under zero-voltage bias operation. During the flame combustion, the CTO/NiO UVC PD exhibits a systematic real-time output voltage change with flame intensity variation, which opens up new possibilities for rapid and accurate fire detection.