We have demonstrated that both carrier multiplication (CM) and hot carrier (HC) effects can be realized through the introduction of an innovative broadband resonant tunneling barrier, specifically utilizing an ultrathin TiOₓ layer within an MoS₂ channel, forming a MoS₂/graphene/TiOₓ heterostructure. This approach enables i) CM effect, with a step-like threshold energy of twice the bandgap, varying with incident laser energies and ii) HC effect, with an increase in open-circuit voltage, enhancing overall energy conversion efficiency. We anticipate an efficiency increase of at least five times compared to existing vdW-based solar cells. Additionally, since all these materials are inorganic and fully passivated by resonant barriers, they offer superior environmental stability against oxidation. This presents a significant advantage over conventional perovskite solar cells, which suffer from degradation and stability issues. Ultimately, our research could pave the way for industrial-scale solar panel production, leveraging vdW-layered materials for highly efficient and stable next-generation photovoltaics.