Photoelectric detectors as the core optoelectronic devices, widely used in civilian imaging, spectroscopy, communications, night vision and so on. Photodetectors are divided into wideband and narrowband detectors by their respective bands. Broadband photodetectors based on Si and InGaAs are capable of responding to photons of any energy greater than their bandgap. Narrow-band detectors, also known as band-division detectors, have wavelength-sensitive properties that can only detect light in a particular band and play an important role in biological imaging and safety monitoring. Constructing a broadband simultaneous band distinguishable photodetector is a challenging and significant exercise, implying that two opposing band-detection features are integrated into the same photodetector, which has never before been reported. In addition, the high sensitivity is also a key parameter of the photodetector, and the high-sensitivity accident detector can respond strongly to the weak signal.
Prof. Tang Jiang from the Functional Photon Function Laboratory for the first time prepared the photodetector with wideband response and wavelength distinguishability for the first time. The related research results have been published in Light: Science & Applications magazine recently published by Nature Publishing Group. The lead sulfide quantum dot sensitized tin disulfide nanosheet composite structure is utilized to fully utilize the performance advantages of quantum dot broad spectrum absorption and high carrier mobility of tin disulfide nanosheets. The prepared photodetector has a response band of 400 to 1000 nm. It has 106 A / W responsivity and 2.2 × 1012 Jones ratio in the infrared band, 105 A / W responsivity and 2.4 × 1011 Jones ratio in the UV range, leading the performance of its kind. More importantly, when the incident photon energy is less than the disulfide bandgap (2.4 eV) but greater than the bandgap (1.2 eV), the photon can only be absorbed by the sulfide Pb quantum dots Of the photo-generated electrons are injected into the tin disulfide nanosheet so that the contact barrier between the tin disulfide nanosheet and the gold electrode becomes higher resulting in a decrease of charge transfer and a negative photoelectric response. When the incident photon energy is greater than the disabling band width of the disulfide, When the tin sulfide and lead sulfide quantum dots absorb light simultaneously, the concentration of photogenerated carriers (electrons and holes) in the tin disulfide nanosheets increases, masking the effect of the increase of the contact barrier, and the positive photoelectric response occurs. Based on the wide spectral response and wavelength distinguishability, the detector successfully distinguishes white LEDs of different color temperatures.
PhD supervisor for the first author of the research paper, Professor Tang Jiang correspondent. The above research work has won the support of the Central Organization Department's "Youth Thousand Talents Program" and the National Natural Science Foundation of China. The research also got the help of Associate Professor Song Haisheng and Dr. Chen Chao, and thanked him for it.
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