Fig. 4: Photodetection performance.

a I_ds-V_ds curves of the WSe₂/H₂O/PdSe₂ device at different power densities of 532 nm laser, here the device exhibits non-conducting behavior in the dark state, and a very weak light illumination can “turn on” the device. The black dashed line shows the average dark-state current of the device, which is ~ 20 fA. The blue dashed line shows the change in open-circuit voltage with increasing laser power. b Extracted switching ratios at different light power densities. c 2D plot of extracted responsivity as a function of bias voltage and light power. Here, the wavelength used is 532 nm, and the data are extracted from Fig. 4a. d Time-dependent photoresponse using a modulated pulsed laser with wavelengths ranging from 375 nm to 4600 nm (UV to MWIR). Here, the response curves at different wavelengths are plotted individually, irrespective of the initial time. The bias voltage used is V_ds = − 2 V. e Frequency response of the device, exhibiting a -3 dB frequency of 0.2 MHz (MWIR, λ = 4600 um). Inset: response speed of the device, showing a 3.2/3.0 μs rise/decay time, respectively. The bias voltage used is V_ds = − 2 V. f Extracted rise/decay time at different wavelengths, from UV to MWIR. The bias voltage used is V_ds = − 2 V. The error bars represent the standard deviations of the same sets. g Polarization photoresponse of the device (λ = 1500 nm and λ = 450 nm), showing a statistical photoresponse characteristic at different polarization angles. h Endurance test under 5000 consecutive laser pulses (532 nm), showing that the dark current remains ultralow and the photocurrent stable throughout. i Atmospheric stability test, where the device maintains stability for up to two years. λ, wavelength; UV, ultraviolet; MWIR, mid-wave infrared.