1：Experimental Design and Method Selection:

The study involves the design of a van der Waals heterostructure photo-diode composed of black phosphorus (p-BP) and palladium diselenide (n-PdSe2). The methodology includes the use of mechanical exfoliation for material preparation, dry transfer method for heterostructure formation, and electron-beam lithography for electrode patterning.

2：2). The methodology includes the use of mechanical exfoliation for material preparation, dry transfer method for heterostructure formation, and electron-beam lithography for electrode patterning. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: Samples include few-layered PdSe2 and BP flakes transferred onto a SiO2/p-type Si substrate. Data sources include electrical and photovoltaic measurements under various conditions.

3：List of Experimental Equipment and Materials:

Equipment includes atomic force microscopy (AFM), Raman spectroscopy, Kelvin probe force microscopy (KPFM), and Keithley semiconductor characterization systems. Materials include BP, PdSe2, Cr/Au, and Sc/Au electrodes.

4：Experimental Procedures and Operational Workflow:

The procedure involves flake transfer, annealing, electrode deposition, and electrical characterization under vacuum. Photovoltaic measurements are conducted under different laser powers and wavelengths.

5：Data Analysis Methods:

Data analysis includes calculating rectification ratio, photoresponsivity, detectivity, and external quantum efficiency from current-voltage characteristics and temporal photoresponse measurements.