Light-emitting perovskite quantum dots (PeQDs) are extensively investigated owing to their evident merits. However, it is still a challenge to adjust their intrinsic emissions and enhance their thermal stability to achieve full-color highly emissive QD-based light-emitting diodes (QLEDs), especially blue QLEDs. Herein, we demonstrate an effective strategy to fundamentally stabilize the crystal structure of CsPbBr 3 QDs by codoping Na + and Cu 2+ ions, which are designed to substitute Cs + (A sites) and Pb 2+ (B sites), respectively. It is found out that the codoping metal ions have significantly improved the thermal stability and the optical properties of the QDs. 40% of the emission intensity can be remained after 8 thermal cycles (20–120 °C) for CsPbBr 3 : Na + /Cu 2+ QDs, whilst less than 10% is maintained for undoped CsPbBr 3 QDs. Accordingly, stable blue QLEDs are packed by CsPbBr 3 : Na + /Cu 2+ QDs. Strong electroluminescence with the maximum luminance of 7161 cd m −2 and low turn-on voltage of 2.4 V are realized. The CIE coordinates are tuned from green (0.10, 0.74) to blue (0.17, 0.25) via Na + and Cu 2+ codoping. The maximum external quantum efficiency (EQE max ) is obtained as 4.52% for PeLEDs based on codoped QDs. The proposed metal ions A and B sites dual substitution strategy guarantees PeQDs as an extremely promising prospect in potential applications as high-resolution displays and high-quality lightings.
Here we report the evaluation of natrochalcite (Na[Cu 2 (OH)(H 2 O)(SO 4 ) 2 ]), an anionic layered structure [Cu 2 (OH)(H 2 O)(SO 4 ) 2 ] − charge-balanced by Na + , as an anode material for both Li- and Na-ion batteries. It delivers 224 mAh/g and 175 mAh/g in the first discharge in the Li + - and Na + -cells respectively, and decomposes to form amorphous matrixes during this step. In the subsequent charge, the original layered structure is unusually partially recrystallized back from the matrixes, resulting in 53 mAh/g and 35 mAh/g discharge capacities in the second discharge respectively. In subsequent cycling, Li + in the electrolyte is found to replace the original Na + during cycling in the Li + -cell and the electrode in the Li + -cell demonstrates better capacity retention rates than that in the Na + -cell, possibly due to Li + being smaller than Na + and thus decomposition-recrystallization cycles being more reversible during cycling in the Li + -cell.
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