Perovskite light emitting diode (PeLED) shows great potential as the next generation HD full-color display technology due to their excellent electroluminescent properties such as high luminous efficiency, tunable luminescence and good color purity. For near-infrared, red and green PeLED, external quantum efficiency (EQE) of more than 20% has been achieved, while the electroluminescence performance of blue PeLED is still inferior to that of similar long-wavelength devices, which seriously hinders the future commercialization of PeLED.

At present, constructing quasi-two-dimensional structure is the most effective solution to modulate perovskite wide-band gap luminescence and manufacture blue PeLED. However, poor n-phase distribution in quasi-two-dimensional perovskite films can lead to low luminous efficiency, wide luminous peak and poor color purity. Therefore, precise regulation of quasi-two-dimensional perovskite components to obtain high purity n-phase distribution is very important for realizing quasi-two-dimensional blue PeLED.

To solve this problem, the research team of GUO Xiaoyang, LV Ying and LIU Xingyuan from Changchun Institute of Optics, Fine Mechanics and Physics of the Chinese Academy of Sciences, further added the bi-functional spacer ligand 2-bromoethylamine hydrobromide (BEABr) to the green quasi-two-dimensional perovskite structure to achieve wide-band gap blue light emission of pure bromine perovskite.

The weak van der Waals gap between perovskites can be reduced through hydrogen bonding and halogen-halogen bonding interactions with the perovskite structure, which effectively improves the energy transfer efficiency and reduces the non-radiative recombination loss, and greatly increases the radiative recombination efficiency of quasi-two-dimensional perovskites.

At the same time, the continuous and concentrated n-phase distribution is realized by using the mixed spaced-cation system to avoid the problem of poor phase distribution affecting the improvement of electroluminescence efficiency. Finally, the obtained sky-blue perovskite LED achieved a maximum EQE of 16.98% at 493 nm, and the device also showed good operating stability.

This work provides a simple and effective strategy for the fabrication of high efficiency blue perovskite light-emitting diodes by regulating quasi-two-dimensional phase distribution.