Fast‐Response Oxygen Optical Fiber Sensor based on PEA2SnI4 Perovskite with Extremely Low Limit of Detection

Abstract Oxygen sensor is an important technique in various applications including industrial process control, medical equipment, biological fabrication, etc. The reported optical fiber‐based configurations so far, using gas‐sensitive coating do not meet the stringent performance targets, such as fast response time and low limit of detection (LOD). Tin‐based halide perovskites are sensitive to oxygen with potential use for sensor applications. Here, the halide perovskite‐based oxygen optical fiber sensor by combining phenylethylammonium tin iodide (PEA 2 SnI 4 ) and tilted fiber Bragg grating (TFBG) is demonstrated. The PEA 2 SnI 4 ‐based oxygen optical fiber sensor is reversible at room temperature with a response time of about 10 s, and the experimental LOD approaches to an extremely low oxygen concentration of about 50 ppm. The as‐fabricated oxygen sensor shows a relative response change of 0.6 dB for an oxygen concentration increase from 50 ppm to 5% with good gas selection against NO 2 , CO, CO 2 , H 2 . This work extends the sensor applications of halide perovskites, providing a novel technique for rapid and repeatable oxygen gas detection at a low level.