Self-assembly In2Se3/SnSe2 heterostructure array with suppressed dark current and enhanced photosensitivity for weak signal

Functional van der Waals (vdWs) heterostructures based on layered materials have shown tremendous potential in next-generation optoelectronic devices. To date, numerous vdWs heterostructures have been investigated based on stacking or epitaxial growth technology. However, the complicated synthesis process greatly limits the large-scale integration of the heterostructure device array, which is essential for practical applications. Here, a planar photodetector array with an out-of-plane vertical In2Se3/SnSe2 heterostructure as the photosensitive channel was self-assembled through a pulsed laser deposition (PLD) technique. The vertical built-in field was exploited to suppress the dark current and separate the photogenerated carriers. The realized devices possess an ultralow dark current of 6.3 pA, combined with a high detectivity of 8.8×1011 Jones and a high signal-to-noise ratio (SNR) beyond 3×104. These performance metrics not only are one order of magnitude superior to pure In2Se3 device, but also demonstrate the unique advantage of detecting weak signals. In addition, this heterostructure photodetector array can further be constructed on flexible polyimide (PI) substrate. These flexible devices also demonstrate effective light detection capability and the photoresponse remains unchanged even after 200 cycles of bending. These findings pave a way toward the development of next-generation large area and high integration optoelectronic technologies.