Lattice reconstruction for mixed-halide blue perovskite light-emitting diodes with high brightness, outstanding color stability and low efficiency roll-off

We report a simple, effective, and universal lattice reconstruction approach to improve the quality of perovskite films by using nonpolar solvents with high Gutmann donor numbers (DNs). We find that high-DN nonpolar solvents, for instance, ethyl acetate, can interact with perovskite precursors. Such a solvent can make the perovskite lattice more ordered and “harder” and promote the formation of heterostructures with low-dimensional perovskite impurities and residual solvent molecules. As a result, the lattice-reconstructed perovskite films exhibit reduced defect densities and suppressed ion migration. The resultant mixed-halide blue perovskite light-emitting diodes (PeLEDs) show greatly enhanced tolerance to high driving current densities and voltages, demonstrating high brightness, outstanding color stability and low efficiency roll-off. Our work provides a deep understanding of the interactions between nonpolar solvents and perovskites and offers useful guidelines for further development of high-power PeLEDs.