Self-Powered Ultra-Broadband p-p MWCNTs/PdO/Si Homomorphic Heterostructure Photodetector for Dual-Channel Encrypted...

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 5.85×10¹³ Jones, and I_light/I_dark ratio exceeding 10⁶ 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.