“Researchers have made significant progress in the field of near-infrared detection technology. By combining NaYF4:4%Er upconversion nanoparticles with perovskite semiconductor layers and utilizing the localized surface plasmon resonance effect of Ag nanorods, they have successfully developed a narrowband upconversion photodetector with a wavelength of 1550 nm. This approach not only enhances upconversion luminescence but also reduces the pump threshold, achieving an optimized responsivity of 48.5 mA/W and a detectivity of 5.7×10^8 Jones. This research provides a simple strategy for constructing stable near-infrared narrowband photodetectors, offering a new solution for the development of high-performance photodetectors.”