Noble metal dichalcogenides (NMDs) are two-dimensional (2D) layered materials that exhibit outstanding thickness-dependent tunable-bandgaps that can be suitable for various optoelectronic applications. Here, we developed high-performance switching photodiodes based on mix-dimensional 2D palladium diselenide (PdSe₂) and three-dimensional (3D) silicon (Si) heterojunctions with a broadband spectral response by a mechanical exfoliation technique. We studied the gate-tunable rectifying behavior of n-PdSe₂/p-Si diodes employing an ionic liquid gate and achieved a maximum diode rectification ratio I_f/I_r up to ∼1.0 × 10⁵ with the lowest value of ideality factor ∼1.22 (at V_tg = −2 V). At different temperatures (60 to 300 K), Zener tunneling and avalanche breakdown phenomena were detected at the junction of PdSe₂–Si. These devices showed excellent self-driven photoresponses over broadband wavelengths from 400 to 1200 nm. The response speed of estimated is 9.2/17.3 μs, which represents a fast photoresponse. Moreover, in our devices, open-circuit voltage (V_OC = 0.6 V) switching behavior is attained with the on/off state of the incident light. Moreover, these devices were attested for dynamic rectification, and this effectively rectified an input alternating-voltage sine wave signal to an output signal. The results of this study indicate that 2D PdSe₂ can be employed for high-performance optoelectronic applications.