Stable blue perovskite light-emitting diodes achieved by optimization of crystal dimension through zinc bromide addition

Low-dimensional perovskites have been widely studied as a promising candidate for realizing stable lightemitting diodes (LEDs). However, blue-light-emitting devices generally possess low stability associated with gradually red-shifted emission. To overcome this issue, the effect of zinc bromide (ZnBr2) addition on the regulation of the crystal structures of phenethylammonium and bromine-chlorine mixed inorganic perovskites (PEA-CsPbBrxCl3-x) is investigated. With the ZnBr2 addition, low-dimensional perovskite structures undergo morphological changes, such as thickening of their crystal structures and higher degree of crystal arrangement. Stoichiometric selective characterization reveals that perovskite bonding forces changed from Van der Waals with PEA to ionic with ZnBr2. Meanwhile, ZnBr2 can effectively address the ion defect filling and dimensional structure property switching. Consequently, the optimized ZnBr2-assisted PEA-CsPbBrxCl3-x LED is shown to deliver a high luminance of 1245 cd/m(2) along with a high external quantum efficiency of 1.30%. Furthermore, this blue LED exhibits excellent spectral stability, for which only 3-nm red-shift on external excitation (0.1 to 5.0 mA) is observed. Our result clearly shows that ZnBr2 addition effectively improves the stability of blue lightemitting perovskites.

Automated summary

The study investigated the effect of adding ZnBr2 to low-dimensional perovskite structures on crystal morphology and optical properties. The results demonstrate that the addition of ZnBr2 can enhance the stability of blue LEDs, leading to higher luminance and external quantum efficiency, as well as excellent spectral stability on external excitation.