Emissions at Perovskite Quantum Dot/Film Interface with Halide Anion Exchange

Solution processable hybrid perovskite film and quantum dots (QDs) have shown promising application in optoelectronic devices owing to their inherent crystal structures, ionics property, and electronic nature. The manipulation of halide anions, for both perovskite bulks and quantum dots, is definitely critical for rendering such materials with peculiar optoelectronic characteristics. Herein, the tunable emissions at the solid interface between CH3NH3PbI3 film and CsPbBr3 quantum dots via halide anion exchange are reported. By in situ photoluminescence and X-ray diffraction measurements, the gradual substitution of Br ions in the CsPbBr3 QDs lattice by I ions in CH3NH3PbI3 film and the reversed ions exchange process is elaborately monitored, respectively. In addition, the morphology of CsPbBr3 QDs on CH3NH3PbI3 film and micronet is preserved according to atomic force microscope and high-magnification scanning electron microscope observations. Furthermore, the time course of the anion exchange can be tuned by tailoring the density of ligands on CsPbBr3 QDs. By exquisite manipulation of halide anions exchange, capability is achieved to tailor the emission color continuously at the microscale. This work expands the understanding of perovskite anion exchange to new dimensions and implies their potential applications in optoelectronic devices owing to the gradient energy level stem from the interfacial transition.