Self‐Powered Ultra‐Broadband p‐p MWCNTs/PdO/Si Homomorphic Heterostructure Photodetector for Dual‐Channel Encrypted Optical Communication and Thermal Monitoring

Ultra‐broadband photodetectors (UB‐PDs) represent a key technological frontier for optical communication and thermal monitoring owing to their monolithically integrated, wide‐spectrum photoresponsivity. However, photocurrent degradation caused by charge‐carrier recombination, which primarily arises from lattice mismatch and interface defects in heterostructures, remains a major limitation on improving the sensitivity and response speed of UB‐PDs. Here, we demonstrate a self‐powered ultra‐broadband UB‐PD based on a p‐p multi‐walled carbon nanotubes (MWCNTs)/PdO/p‐Si homomorphic heterostructure with enhanced photoelectronic characteristics for dual‐channel encrypted optical communication and thermal monitoring. The device exhibits exceptional photoelectronic performance across an exceptionally broad spectral range (365 nm to the mid‐infrared, MIR) at room temperature, achieving a self‐powered responsivity ( R ) of 0.72 A/W, detectivity ( D* ) of 5.85×10 13 Jones, and I light /I dark ratio exceeding 10 6 under 0 bias. The enhanced photoresponse is attributed to three synergistic effects: (i) suppression of non‐radiative charge‐carrier recombination, (ii) increased photocurrent and accelerated response speed enabled by the p‐p heterostructure, and (iii) improved MIR absorption driven by the MWCNTs. We also design a dual‐channel encrypted optical communication system which implemented the ultra‐broad spectral cooperative encryption communication with enhanced security on a single device. We further apply the MWCNTs/PdO/p‐Si heterojunction photodetector to develop a distance‐independent colorimetric thermal monitoring system.