Ultrabroadband, Self‐Powered, Highly‐Sensitive Photodetector Based on Bi ₂ Te ₃ /Graphene Heterostructure Synergistically Enhanced with Photothermal Mechanisms and Au Antenna

Abstract Ultrabroadband photodetectors (UB‐PDs) are essential in various application scenarios. However, the development of existing UB‐PDs is still limited by device performance and operating conditions. Research on self‐powered ultrabroadband photodetectors is urgently needed. This study demonstrates a van der Waals heterostructure composed of Au‐Bi ₂ Te ₃ ‐graphene, which enables self‐powered visible‐to‐millimeter wave detection through a synergistic conversion mechanism of optical field modulation, structural thermal management, and strong thermoelectric coefficient asymmetry. The device's ability to harvest low‐energy photons (millimeter waves (MMW) to terahertz (THz)) is enhanced by integrating a metal‐coupled antenna structure. Furthermore, the design incorporates thermoelectric asymmetry conditions derived from multiple perspectives and mechanism, substantially enhancing the electric potential difference. For the first time in this material system, the device achieves ultrabroadband response and terahertz band performance with a peak responsivity of 6.29 A·W ⁻¹ at 340 GHz. Demonstrations of terahertz imaging and millimeter‐wave coded communication have verified its potential for use in multiple scenarios. This research result demonstrates an ultrabroadband detection method that achieves high response and self‐driving through the optimization and coordination of multiple physical variables under a single driving mechanism. It opens new avenues for the future development of complex scenes, multifunctional, and miniaturized photoelectric detection technology.