Ultrasmall SnS₂ quantum dot-based photodetectors with high responsivity and detectivity

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Quantum dots (QDs) exhibit unique properties due to quantum confinement and high surface-to-volume ratios.
• Producing homogeneous QDs, especially tin disulfide (SnS2), presents significant challenges.
• Existing SnS2-based photodetectors often require external bias and have limited sensitivity.

Purpose of the Study:

• To develop a high-yield method for preparing ultrasmall tin disulfide quantum dots (SnS2 QDs).
• To construct and characterize self-powered photoelectrochemical photodetectors (PDs) using these SnS2 QDs.
• To investigate the performance and working mechanism of SnS2 QD-based PDs for enhanced optoelectronic applications.

Main Methods:

• Combined top-down and bottom-up approaches for SnS2 QD synthesis.
• Fabrication of self-powered photoelectrochemical-type photodetectors (PDs) with SnS2 QDs as photoelectrodes.
• Characterization of QD properties and PD performance, including photocurrent density and photoresponsivity.
• Utilized density functional theory (DFT) calculations and optical absorption spectroscopy to elucidate the device mechanism.

Main Results:

• Successfully synthesized high-yield, ultrasmall SnS2 QDs with uniform dimensions (3.17 ± 0.62 nm lateral size, 2.39 ± 0.88 nm thickness).
• Developed self-powered PDs exhibiting a high photocurrent density (16.38 μA cm⁻²) and photoresponsivity (0.86 mA W⁻¹).
• Demonstrated robust long-term cycling stability and superior weak-light sensitivity, even at zero bias voltage.

Conclusions:

• Ultrasmall SnS2 QDs can be effectively prepared using a hybrid synthesis approach.
• The developed SnS2 QD-based PDs show promising performance for self-powered and highly sensitive optoelectronic applications.
• This work offers a new pathway for designing advanced QD-based optoelectronic devices.