Room Temperature long-wavelength infrared Sensitive Imaging Photodetection based on topological insulator Bi2Te3 nanoflakes

The room temperature long-wavelength infrared (LWIR) sensitive photodetector is realized using topological insulator (TI) bismuth telluride (Bi2Te3) nanoflakes. Conventional mid-/LWIR detectors require energy-intensive cryo-coolers due to the intrinsic bottleneck of exponentially rising dark current, a challenge overcome by this new approach. The Bi2Te3 exhibits an anomalous temperature dependence photoluminescence (TDPL) phenomenon: they emit intense LWIR photoluminescence at room temperature, and—contrary to the usual thermal quenching—their emission strength increases with temperature, satisfying a key prerequisite for room-temperature LWIR photodetector. Even with a simple photoconductive architecture, the detector achieves background-limited performance at 300 K, showing a specific detectivity D* of 3 × 108 Jones at 10.6 μm and 1.37 × 109 Jones at 55 μm. Furthermore, clear “HIT” “CUST” pixel images with distinct edge contours were obtained through illuminated by a 600 °C blackbody source at room temperature. The suppression of thermal noise is attributed to the unique carrier transport mechanism where the electron-phonon interaction operator acts as an annihilation operator during detection. Furthermore, the topological edge states of Bi2Te3, protected by spin-orbit coupling and time-reversal symmetry, are robust against surface defects and effectively suppress trap-induced thermal noise. These findings highlight the potential of TI-based materials for developing high-performance, uncooled mid-/LWIR and terahertz detection and imaging systems.