Broadband Nonlinear Photoresponse and Ultrafast Carrier Dynamics of 2D PdSe2

Abstract Palladium diselenide (PdSe 2 ) exhibits considerable potential for application in broadband optoelectronic devices. In this work, the broadband nonlinear optical performance and ultrafast carrier dynamics from ultraviolet to near‐infrared of a trilayer PdSe 2 are systematically studied. PdSe 2 is found to achieve a giant saturable absorption performance. The modulation depth is 22.47% at 520 nm, whereas the nonsaturable loss and saturation intensity are only 3.83% and 15.47 GW cm −2 , respectively, which are better than those of many 2D semiconductors. Based on these findings, a PdSe 2 ‐based visible light thresholder is proposed, its function is to extract an undetectable pulse signal drowned in strong stochastic noise and thereby improve the signal‐to‐noise ratio. Pump–probe technique, along with first‐principles calculation and transient absorption spectra, reveals the intrinsic recombination mechanism, including Auger scattering and trap saturation. This work is expected to establish the foundation for the development of next‐generation PdSe 2 ‐based devices in optoelectronics and visible light communication.