Efficient single-component white light emitting diodes enabled by lanthanide ions doped lead halide perovskites via controlling Förster energy transfer and specific defect clearance

Currently, a major challenge for metal-halide perovskite light emitting diodes (LEDs) is to achieve stable and efficient white light emission due to halide ion segregation. Herein, we report a promising method to fabricate white perovskite LEDs using lanthanide (Ln(3+)) ions doped CsPbCl(3) perovskite nanocrystals (PeNCs). First, K(+) ions are doped into the lattice to tune the perovskite bandgap by partially substituting Cs(+) ions, which are well matched to the transition energy of some Ln(3+) ions from the ground state to the excited state, thereby greatly improving the Förster energy transfer efficiency from excitons to Ln(3+) ions. Then, creatine phosphate (CP), a phospholipid widely found in organisms, serves as a tightly binding surface-capping multi-functional ligand which regulates the film formation and enhances the optical and electrical properties of PeNC film. Consequently, the Eu(3+) doped PeNCs based-white LEDs show a peak luminance of 1678 cd m(-2) and a maximum external quantum efficiency (EQE) of 5.4%, demonstrating excellent performance among existing white PeNC LEDs from a single chip. Furthermore, the method of bandgap modulation and the defect passivation were generalized to other Ln(3+) ions doped perovskite LEDs and successfully obtained improved electroluminescence (EL). This work demonstrates the comprehensive and universal strategies in the realization of highly efficient and stable white LEDs via single-component Ln(3+) ions doped PeNCs, which provides an optimal solution for the development of low-cost and simple white perovskite LEDs.