Bright and efficient blue emission is key to further development of metal halide perovskite light-emitting diodes. Although modifying bromide/chloride composition is straightforward to achieve blue emission, practical implementation of this strategy has been challenging due to poor colour stability and severe photoluminescence quenching. Both detrimental effects become increasingly prominent in perovskites with the high chloride content needed to produce blue emission. Here, we solve these critical challenges in mixed halide perovskites and demonstrate spectrally stable blue perovskite light-emitting diodes over a wide range of emission wavelengths from 490 to 451 nanometres. The emission colour is directly tuned by modifying the halide composition. Particularly, our blue and deep-blue light-emitting diodes based on three-dimensional perovskites show high EQE values of 11.0% and 5.5% with emission peaks at 477 and 467 nm, respectively. These achievements are enabled by a vapour-assisted crystallization technique, which largely mitigates local compositional heterogeneity and ion migration.

Antibiotic resistant pathogens is the an urgent challenge of the medicine field. To counter these pathogens, the antibiotic assisting drugs is an ideal choice. Assisting drugs can improve the efficiency of the treatment without further induce of antibiotic resistance. Amlodipine (AML) is one of the most common generic cardiovascular drug for lowering blood pressure. In previous studies, amlodipine was suggested to have some antibiotic properties. The MIC is not very low for amlodipine against these pathogens. However, the findings imply amlodipine potential to be repurposed as assisting drug and its inhibition of β-lactamase. To further discover and verify its potential of antimicrobial drug, amlodipine was tested for β-lactamase inhibition, and its synergistic effects were investigated against methicillin-resistant Staphylococcus aureus (MRSA). The compound was found to inhibit β-lactamase mixture (3 distinct species) in broad spectrum. Cephalosporins requires high concentration (>=64 ug/ml) to inhibit MRSA; combine both amlodipine and cephalosporins, the MIC only requires 8ug/ml (4 ug/ml amlodipine + 4 ug/ml Cefuroxime) in total, with FIC lower than 0.1 for strong synergistic effect. Both enzyme assay and bacterial tests indicate amlodipine as an ideal assisting drug for antibiotics; one of the mechanism is β-lactamase inhibition.

Bright and efficient blue emission is key to further development of metal halide perovskite light-emitting diodes. Although modifying bromide/chloride composition is straightforward to achieve blue emission, practical implementation of this strategy has been challenging due to poor colour stability and severe photoluminescence quenching. Both detrimental effects become increasingly prominent in perovskites with the high chloride content that is desired to produce blue emission. Here, we solve these critical challenges in mixed halide perovskites and demonstrate spectrally stable blue perovskite light-emitting diodes (PeLEDs) over a wide range of emission wavelengths from 490 to 451 nanometres. The emission colour is directly tuned by modifying the halide composition. Particularly, our blue and deep-blue PeLEDs based on three-dimensional perovskites show high EQE values of 11.0% and 5.5% with emission peaks at 477 and 467 nm, respectively. These achievements are enabled by a vapour-assisted crystallization technique, which largely mitigates local compositional heterogeneity and ion migration.

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