Manipulating Crystallization Dynamics for Efficient and Spectrally Stable Blue Perovskite Light-Emitting Diodes

Reduced-dimensional perovskite light-emitting diodes (PeLEDs) have shown great potential in solution-processed high-definition displays. However, the inferior electroluminescent (EL) performance of blue PeLEDs has become a huge challenge for their commercialization. The inefficient domain control [number of PbX₆⁻ layers (n)] and deleterious phase segregation make the blue PeLEDs suffer from low EL efficiency and poor spectral stability. Here, a rational strategy for perovskite crystallization control by adjusting the precursor concentration is proposed for improving phase distribution and suppressing ion migration in reduced-dimensional mixed-halide blue perovskite films. Based on this method, efficient sky-blue PeLEDs exhibit a maximum external quantum efficiency (EQE) of 8.5% with stable EL spectra at 482 nm. Additionally, spectrally stable pure-blue PeLEDs at 474 and 468 nm are further obtained with maximum EQEs of 4.0% and 2.4%, respectively. These findings may provide an alternative scheme for manipulating perovskite crystallization dynamics toward efficient and stable PeLEDs.