Efficient blue electroluminescence from reduced-dimensional perovskites

Perovskite light-emitting diodes (LEDs) show promises for next-generation displays owing to their excellent luminescent properties and low cost. Despite substantial progress with green- and red-emitting devices, the development of efficient blue perovskite LEDs has lagged behind. Here we demonstrate efficient blue perovskite LEDs based on a mixed two-dimensional–three-dimensional perovskite and a multifunctional ionic additive that enables control over the reduced-dimensional phases, non-radiative recombination channels and spectral stability. We report a series of devices that emit efficient electroluminescence from mixed bromide/chloride quasi-three-dimensional regions, with external quantum efficiencies of up to 21.4% (at a luminance of 22 cd m –2 and emission peak at 483 nm), 13.2% (at a luminance of 2.0 cd m – 2 and emission peak at 474 nm) and 7.3% (at a luminance of 6 cd m –2 and emission peak at 464 nm). Devices show a nearly 30-fold increase in operational stability compared with control LEDs, with a half-lifetime of 129 min at an initial luminance of 100 cd m –2 . Our findings demonstrate the performance of blue perovskite LEDs close to that of state-of-the-art blue organic LEDs and inorganic quantum dot LEDs and provide a new approach to design multifunctional molecules to boost the performance of perovskite optoelectronic devices.