Fig. 2: Two-color performance characterization and colorimetric temperature measurement.

a Dark current characteristics of bP/MoS₂ heterojunction photodiode in 300 K without illumination. Inset: the J-V characteristics of the device with or without a 1200 K blackbody source. b Dark current characteristics of Si/MoS₂ heterojunction photodiode in 300 K without illumination. Inset: the J-V characteristics of the device with or without a 1200 K blackbody source. c Specific detectivity at different blackbody temperatures. d Normalized spectral response of the two-color photodetector during the back radiation. The 0.7–1.3 μm of the spectrum was measured by a grating spectrometer. The 1.3–4.5 μm of the spectrum was measured by FTIR. All FTIR and laser diode characterization were performed at a bias of 0 V (MWIR) and −0.5 V (NIR). e Specific detectivity as a function of wavelength measured for a bP/MoS₂/Si heterojunction at room temperature as well as various commercially available and reported NIR/MWIR two-color photodetectors, including MCT/Si (Kunming Institute of Physics), InGaAs/Si (Hamamatsu K1713-08) and InAsSb/Si (Hamamatsu K1713-003). All FTIR and laser diode characterization was performed at a bias of 0 V. The black line in the figure is the performance limit of photovoltaic devices; the red line is the performance limit of thermoelectric device; the gray box is commercial thermistor. f Left axis, NIR and MWIR signals as a function of photodetector–blackbody distance. Right axis, the relationship between the NIR/MWIR ratio and photodetector–blackbody distance. g NIR/MWIR ratio depends on the blackbody temperature. Red dots show the measured NIR/MWIR ratio in each blackbody temperature