  Topological insulators have shown great potential for future optoelectronic
technology due to their extraordinary optical and electrical properties.
Photodetectors, as one of the most widely used optoelectronic devices, are
crucial for sensing, imaging, communication, and optical computing systems to
convert optical signals to electrical signals. Here we experimentally show a
novel combination of topological insulators (TIs) and transition metal
chalcogenides (TMDs) based self-powered photodetectors with ultra-low dark
current and high sensitivity. The photodetector formed by a MoS2/Sb2Te3
heterogeneous junction exhibits a low dark current of 2.4 pA at zero bias and
1.2 nA at 1V. It shows a high photoresponsivity of > 150 mA W-1 at zero bias
and rectification of 3 times at an externally applied bias voltage of 1V. The
excellent performance of the proposed photodetector with its innovative
material combination of TMDs and TIs paves the way for the development of novel
high-performance optoelectronic devices. The TIs/TMDs transfer used to form the
heterojunction is simple to incorporate into on-chip waveguide systems,
enabling future applications on highly integrated photonic circuits.
