Integrated Pristine van der Waals Homojunctions for Self-Powered Image Sensors

Van der Waals junctions hold significant potentials for various applications in multifunctional and low-power electronics and optoelectronics. The multistep device fabrication process usually introduces lattice mismatch and defects at the junction interfaces, which deteriorate device performance. Here the layer engineering synthesis of van der Waals homojunctions consisting of 2H-MoTe₂ with asymmetric thickness to eliminate heterogenous interfaces and thus obtain clean interfaces is reported. Experimental results confirm that the homostructure nature gives rise to the formation of pristine van der Waals junctions, avoiding chemical disorders and defects. The ability to tune the energy bands of 2H-MoTe₂ continuously through layer engineering enables the creation of adjustable built-in electric field at the homojunction boundaries, which leads to the achievement of self-powered photodetection based on the obtained 2H-MoTe₂ films. Furthermore, the successful integration of 2H-MoTe₂ homojunctions into an image sensor with 10 × 10 pixels, brings about zero-power consumption and near-infrared imaging functions. The pristine van der Waals homojunctions and effective integration strategies shed new insights into the development of large-scale application for two-dimensional materials in advanced electronics and optoelectronics.