Hybrid heterostructures are a promising type of materials framework for optoelectronic conversion. We designed a ternary energy-dependent thin layer of Cu2S-Pt-WO3 (p-type-metal-n-type) heterojunction to explore an alternative way of realizing efficient charge separation. First-principles calculations showed that the Fermi level of the whole system is lined up via the mediation of Pt metal, which fosters the combination of holes in Cu2S and electrons in WO3 and keeps electrons in Cu2S and holes in WO3 well separated. Importantly, creation of band bending and charge polarization steer low-energy charges selectively to the intermediate metal and keep high-energy charges on individual semiconductors apart. Our simulation analysis of two-dimensional layers with the metal bridge shows increased charge flows across the junction compared to that of their bulk counterparts. Overall, this heterojunction is viable for suppressing recombination of photogenerated electron-hole pairs and augmented electrons per surface that would allow enhanced optoelectronic conversion.