Leveraging a Stable Perovskite Composite to Satisfy Blue Electroluminescence Standards

Blue electroluminescence is fundamental for many optoelectronic and lighting applications, and mixed halide perovskite light-emitting devices are under development to meet the technological demands. However, the stability of blue perovskite devices is lacking, primarily because of the halide segregation during operation that degrades the underlying perovskite structure. Saturated and stable blue emission was accomplished with a rational materials blend of a mixed halide perovskite, polymer electrolytes, and a lithium salt that selectively suppressed perovskite ion motion while facilitating the transport of the salt additive. This approach produced blue electroluminescence peaked at 464 nm that surpassed standard benchmarks with a luminance maximum of 540 cd/m2 and stable operation under constant current driving. The role of the polymer and salt additives was explored by photoluminescence, electroluminescence, scanning electron microscopy, and atomic force microscopy studies. Concerning the device, the salt ions improve electrical double layer formation and selectively move in place of the perovskite ions, while the polymers improve the uniformity and smoothness of the films. Fundamentally, each component is shown to contribute to the suppression of halide segregation for highly stable electroluminescence.