Facile Nanogold–Perovskite Enabling Ultrasensitive Flexible Broadband Photodetector with pW Scale Detection Limit

Abstract Broadband photodetection is central to spectroscopy, imaging, and sensing in modern science and technology. However, traditional devices suffer from a higher dark current because as‐adopted photoactive semiconductors tend to be accompanied by a large noise output due to higher conductivity, resulting in low sensitivity and detectivity. The utilization of photon manipulation as enhancing light–matter interaction on a deep subwavelength scale provides a fascinating opportunity to achieve higher photocurrent while keeping a low noise level. Here, an ultrasensitive flexible broadband photodetector based on multiphysics coupled nanogold–perovskite films is demonstrated. The mechanism involves optimized interfacial injection, bulk transport, photon trapping, and energy transformation, and leads to high photosensitivity (≈10⁵), low detection limit (5.7 pW), and wide spectral response (UV–vis–NIR). These results show that the nanometal–perovskite framework can be used as a powerful platform for ultrasensitive flexible broadband photodetection, competitive with state‐of‐the‐art commercial devices or publications.