Gate-tunable dual-mode polarization-sensitive PdSe2/WSe2 2D photodetector for anti-interference recognition

Polarization-sensitive optical sensing and low-speed optical signal decoding are of interest for multifunctional optoelectronic devices. The existing solutions often rely on separate sensors or bulky filtering schemes that increase system complexity and remain vulnerable to glare-induced saturation and false triggering. Here, we present a single, gate-tunable PdSe2/WSe2 2D heterostructure photodetector for laboratory proof-of-concept environmental sensing and low-speed optical signal decoding, combining self-powered operation, 400–900 nm visible–near-infrared (NIR) responsivity, gate-programmable photocurrent polarity switching, and electrically tunable polarization sensitivity. The device leverages the intrinsic in-plane anisotropy of orthorhombic PdSe2 and the built-in fields at the Au/WSe2 contact and the PdSe2/WSe2 interface; the observed gate dependence is consistent with electrostatic modulation of their relative influence, providing a qualitative interpretation of photocurrent polarity and amplitude. The PdSe2/WSe2 2D photodetector exhibits clear polarization-dependent responsivity across the measured 400–900 nm visible–NIR range, stable time-resolved switching endurance, and suppressed dark current. Under an optimized gate bias, the device yields a positive response to 808 nm and a negative response to 532 nm illumination, enabling direct color discrimination by polarity, while the polarization ratio tuning permits selective suppression of linearly polarized optical interference while retaining a measurable response to unpolarized traffic-signal illumination under controlled laboratory conditions. In a laboratory proof-of-concept demonstration, the device discriminates Standby/Stop/Go states under selected illumination wavelengths and polarization conditions using predefined photocurrent thresholds. Measured responses under four gate-voltage and polarization conditions are then used to reconstruct an encoded sequence in post-processing. This compact, multifunctional platform demonstrates the potential of a single reconfigurable photodetector for polarization-selective sensing and low-speed optical signal decoding under controlled laboratory conditions.