Designing a high-efficiency graphene/black phosphorus/graphitic ZnO van der Waals heterostructure for enhanced optoelectronic performance: A first-principles study

Two-dimensional (2D) van der Waals heterostructures are promising platforms for next-generation optoelectronic devices due to their unique electronic and optical properties. In this study, we use density functional theory (DFT) with the GGA-PBE functional implemented in CASTEP to investigate a novel three-layer heterostructure composed of graphitic zinc oxide (g-ZnO), black phosphorus (BP), and graphene (G). The optimized structure shows lattice mismatches below 5 % and a stable interlayer binding energy of 33.5 meV per atom. Molecular dynamics simulations at 900 K demonstrate enhanced thermal stability due to graphene incorporation, significantly suppressing temperature-induced fluctuations compared to BP/g-ZnO bilayers. Electronic structure analyses reveal direct band gaps with type-I alignment for both BP/g-ZnO and G/BP/g-ZnO systems. Importantly, graphene introduces additional electronic states near the Fermi level through orbital hybridization, interlayer interactions and strain effects, disrupting the Dirac point and enhancing carrier transport. Optical properties analysis indicates that the G/BP/g-ZnO heterostructure exhibits red-shifted absorption peaks and improved absorption coefficients across a broad spectral range, leading to increased photocurrent generation and device efficiency from 3.5 % up to 14.7 %. These findings highlight the potential of this heterostructure for high-performance optoelectronic applications.