The paper presents the fabrication and characterization of atomically thin p-n junctions using van der Waals (vdW) heterostructures of transition metal dichalcogenides (TMDCs). The authors demonstrate that these junctions exhibit gate-tunable diode-like current rectification and photovoltaic response, driven by interlayer recombination of majority carriers. The study highlights the unique charge transport and optoelectronic properties of these vdW p-n junctions, which differ significantly from conventional bulk junctions due to the absence of a depletion region. By sandwiching the p-n junction between graphene layers, the authors enhance the collection of photoexcited carriers, achieving a significant improvement in photocurrent collection. The work provides a foundation for the development of high-performance electronic and optoelectronic devices based on atomically thin p-n junctions.The paper presents the fabrication and characterization of atomically thin p-n junctions using van der Waals (vdW) heterostructures of transition metal dichalcogenides (TMDCs). The authors demonstrate that these junctions exhibit gate-tunable diode-like current rectification and photovoltaic response, driven by interlayer recombination of majority carriers. The study highlights the unique charge transport and optoelectronic properties of these vdW p-n junctions, which differ significantly from conventional bulk junctions due to the absence of a depletion region. By sandwiching the p-n junction between graphene layers, the authors enhance the collection of photoexcited carriers, achieving a significant improvement in photocurrent collection. The work provides a foundation for the development of high-performance electronic and optoelectronic devices based on atomically thin p-n junctions.