Large-Area, Flexible, and Dual-Source Co-Evaporated Cs3Cu2I5 Nanolayer to Construct Ultra-Broadband Photothermoelectric Detector from Visible to Terahertz

Metal halides show a powerful potential to fabricate photothermoelectric (PTE) detectors due to their merits of ultra-low thermal conductivity, high Seebeck coefficient, and high carrier mobility. It is critically important to develop a flexible, transparent, and large-area PTE material for pushing its practical and extensive application. In this report, we fabricate a PTE-based detector employing lead-free Cs3Cu2I5 nanolayered film, which is prepared on a large area using a dual-source co-evaporation technique. Importantly, the PTE detector exhibits self-powered light response wavelengths ranging from visible (532 nm) to near-infrared (980 nm) to terahertz (119 μm). Moreover, we find that the photocurrent generation of the Cs3Cu2I5 photodetector by employing lateral device architecture is mainly originated from the PTE effect of Cs3Cu2I5 film. The PTE photodetector arrays incorporated with large-area Cs3Cu2I5 film also provide a successful application in flexible imaging. The results show that lead-free Cs3Cu2I5 is a promising PTE material for fabricating a flexible and self-powered ultra-broadband photodetector and provide insight into the utility of metal halides in thermal-induced ultra-broadband photodetection.