Electrochemical control of photoelectric performance in WS₂/WSe₂van der Waals heterostructures device

Electrochemical intercalation is an effective method for modulating the physical properties of materials, extensively utilized in optimizing device performance in two-dimensional materials. However, research about the modulation on the optoelectronic performance is still lacking. Here, we demonstrate using lithium-ion intercalation to modulate the optoelectronic performance of WS2/WSe2 heterojunction. We observe a significant increase of device conductivity (approximately 50x) after lithium-ion intercalation. At the same time, the peak responsivity increases by 8 times and can be modulated from 8 mA/W to -6 mA/W, accompanied with a reversal of photocurrent direction. No phase transitions are observed throughout the intercalation process by Raman spectroscopy. The variations in photocurrent response are attributed to the injection of free charge carriers and the corresponding alterations in the band structure. Our work paves the way for modulating the optoelectronic performance of two-dimensional materials with electrochemical intercalation.