Gate-Switchable Photovoltaic Effect in BP/MoTe₂ van der Waals Heterojunctions for Self-Driven Logic Optoelectronics

Recently, van der Waals heterojunction based on 2D materials emerges as a promising technology for optoelectronic integrated circuits. Here, a self-driven optoelectronic logic device is demonstrated based on vertically stacked van der Waals heterojunction of black phosphorus and molybdenum telluride. Through the electrostatic doping by gating, the heterojunction is dynamically tuned to isotype (p-P and n-N) and anisotype (p-N) while the built-in electric field in the heterojunction is greatly changed. Consequently, the photovoltaic effect in the heterojunction is switchable by the gate voltage, enabling a novel self-driven optoelectronic logic element without the need of external biasing. This optoelectronic logic device shows promising characteristics of output dark current <1 pA, on/off current ratio >10⁵, switching time <10 µs, broadband operation in the spectral range from 400 to 1600 nm, and linearly adjustable output current. The results may open up unprecedented opportunities to employ van der Waals heterojunctions for exploring logic optoelectronics with high performance and low power consumption.