Atomic-Scale Interface Engineering for Constructing p-CuPc/n-CdS Core-Shell Heterojunctions toward Light-Harvesting Application

Benefiting from the intrinsically different and complementary electronic functionalities, organic/inorganic semiconductor heterostructures offer many tantalizing opportunities to create high-performance, low-cost, multifunctional optoelectronic devices. Compared with their bulk counterparts, organic/inorganic core-shell heterojunction nanowires (NWs) possess superior performances in terms of fewer interface defects, sufficient interfacial interactions, and high carrier collection efficiency, as well as easy and flexible device integration. However, the precise spatial control and large-area synthesis of organic/inorganic core-shell heterostructures currently remain a complex and daunting task, mainly due to the large lattice mismatch and the energetically unfavorable nucleation interface between two distinct chemical constituents. Here, an organic NW-guided atomic layer heteroepitaxy strategy is developed to realize large-scale and spatially controlled synthesis of a new type of semiconductor heterostructures made of p-type single-crystalline copper phthalocyanine (CuPc) and n-type polycrystalline cadmium sulfide (CdS). By rationally engineering the surface chemistry of the organic NWs and controlling the nucleation condition of the CdS, p-CuPc/n-CdS heterostructures with on-demand structural morphologies and optical properties can be constructed. In addition, the delicately designed p-CuPc/n-CdS core-shell NWs exhibit good photovoltaic behavior and excellent photosensitivity with broadband spectrum detection from ultraviolet-visible to near-infrared. This work provides a promising route for developing novel functional p-CuPc/n-CdS core-shell heterojunctions, while demonstrating the great potential of this new type of hybrid system in high-performance broadband photodetection and photovoltaic device application.