Metasurface‐Controlled Highly Sensitive CsFAMA/PEDOT: PSS Heterojunction Terahertz Thermoelectric Polarization Detection and Imaging

Abstract Developing highly sensitive and stable terahertz (THz) polarization detection and imaging systems is crucial for remote sensing, communication, military surveillance, and imaging. However, achieving high sensitivity and stability while effectively suppressing background interference in complex target imaging presents several significant challenges. Herein, two different metasurface structures (type I and type II) and different Cs 0.05 (FA 0.85 MA 0.15 ) 0.95 Pb(I 0.85 Br 0.15 ) 3 (CsFAMA) thicknesses of THz polarization detectors are designed and fabricated, which based on CsFAMA /poly(3,4‐ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS)/ Metasurface composite structures. The type II device with a 0.8 µm CsFAMA thickness achieved optimal performance under 0.1 THz laser irradiation, with a responsivity of 435.81 V W⁻¹, a polarization ratio of 2.53, and a fast response time of 93 µs, attributed to the heterojunction and metasurface‐localized thermoelectric field. In addition, stability tests are carried out under standard conditions, the polarization ratio decreased by only 3%, and further accelerated aging tests at high temperature and high humidity revealed that the polarization ratio decreased by 15% and 27%, respectively. The polarization imaging clearly and distinctly shows three different complex patterns even after 360 days of air exposure. This study highlights the potential of CsFAMA/metasurface composite devices for highly sensitive and stable THz polarization detection and imaging applications.