Overcoming lattice mismatch for heterostructures

Abstract The formation of core-shell heterostructures allows direct contact for more efficient energy transfer and requires exquisite lattice match. Lattice mismatch is one of the most challenging obstacles for combining two components with different phases. In this work, we develop a strategy to successfully overcome the limitation of lattice mismatch for the first time andgrow α-phase lead halide perovskites (LHPs) onto β-phase lanthanide nanoparticles (LnNPs) by seeding ultrasmall sub-5 nm LnNPs. This LnNP@LHP heterostructure enables more efficient two-way energy transfer within the heterostructures. Downconversion and upconversion emissions can be achieved under ultraviolet and near-infrared excitation, respectively. In addition, LHP has a high tolerance for defects and will passivate LnNPs for enhanced fluorescent performance. We identify and prove that size instead of phase is critical to overcome the lattice mismatch. Our strategy has uncovered fresh insights into the key factor of direct epitaxial growth for heterostructures and we believe the current synthesis strategy for high-quality heterostructures will have strong application potential in optoelectronics, anticounterfeiting and light detection etc.