Recently, a research team led by Prof. FEI Guangtao and Prof. XU Shaohui from the Institute of Solid State Physics, Hefei Institutes of Physical Science obtained high-performance visible-near IR photodetectors based on high-quality Sn2+-sensitized PbS films.
Photodetection has broad application prospects in the fields of environmental monitoring, optical communication, biomedical imaging, military warning, etc. PbS is a direct bandgap semiconductor with high light absorption coefficient, which is very suitable for detection of visible-near IR light, but shows poor photoelectric performance.
"The traditional methods to improve the photoelectric performance have many problems, such as poor repeatability, difficulty in mass production, or potential safety hazards,” said Prof. XU, "so we added Sn2+ into PbS precipitation solution by a simple and low-cost chemical bath deposition, and obtained the high-quality Sn2+-sensitized PbS films.”
By improving the ordering of the crystal structure of PbS, enlarging the grain size, and introducing sensitizing centers, the team successfully increased photoresponsivity more than 9 times, and the response speed reaches an order of microseconds.
"The excellent stability and switching behavior surprised us,” said XU, “especially it’s under the high-frequency pulsed light illumination of 4 kHz.”
This excellent photoelectric characteristic of Sn2+-sensitized PbS can rival or surpass many other photodetectors. Herein, Sn2+-sensitized PbS films have been demonstrated the viability to improve the detection performance of commercial photodetectors.
This work was supported by the National Natural Science Foundation of China.
Fig. 1 (a) Photocurrent of pure PbS and Sn2+ sensitized PbS film photodetectors in the visible-near IR range. (b) Response Rate. (c) Normalized I-t curve of Sn2+-sensitized PbS films photodetectors under 4 kHz high-frequency pulsed light. (Imaged by XIA Kai)
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