On‐Chip‐Integrated Methylammonium Halide Perovskite Optical Sensors

Abstract Label‐free, real‐time, portable, and cost‐effective detection of nanoscale objects is central to early‐stage detection of fatal diseases, environmental monitoring, homeland security, and so on. Owing to their extremely large Q/volume and enhanced light–matter interaction, micro‐ and nanophotonic sensors are intensively studied and their performances are significantly improved. To date, single molecule, single virus, and single nanoparticle have been successfully monitored with microscopic and spectroscopic systems, e.g., high‐Q microcavities and plasmonic devices. However, the current technologies suffer from drawbacks such as instability to ambient vibration, long analyzing time, and high costs. Their widespread uses, especially in portable point‐of‐care devices, are strongly hindered. Herein, taking full advantages of methylammonium lead tri‐halide (MAPbX₃) perovskite, the perovskite photodetectors with Si₃N₄ waveguides are integrated and their potential in on‐chip‐integrated optical sensors is demonstrated. With a simple laser diode, single nanoparticle with radius ≈70 nm is successfully gauged for the first time.