Size tunable and controllable synthesis of PbS quantum dots for broadband photoelectric response

PbS quantum dots (QDs) with size-dependent photoelectric characteristics and wide spectral absorption show a great potential material for preparing near-infrared photodetectors, attracting numerous studies. This paper prepared size-tunable PbS QDs with a mean size varying from 3 nm to 9 nm via a modified hot injection method. And the effects of different factors on the size of PbS QDs in the synthesis were systematically summarized. Moreover, size-dependent optoelectronic properties of PbS QDs were studied. With the increase in size, the dark current, photocurrent, and responsivity of devices show an increase, while the 3 dB bandwidth decreases. In addition, the larger the size, the wider the detection spectrum coverage, the detectivity of the corresponding absorption peak in PbS QDs is better than another size PbS QDs, but the maximum detectivity of the large size PbS QDs is lower than that of the small size PbS QDs in the near-infrared. Therefore, selecting different PbS QDs to prepare photodetector is of great significance for practical applications with different detection requirements. Significantly, these size-tunable PbS QDs photodetectors show fast response and excellent responsivity, and detectivity.