Journal
ADVANCED SCIENCE
Volume 9, Issue 20, Pages -Publisher
WILEY
DOI: 10.1002/advs.202200393
Keywords
alkali metal halide; domain distribution; perovskite light-emitting diode; quasi-2D perovskite
Categories
Funding
- China Postdoctoral Science Foundation [2020M680498]
- Shenzhen Science and Technology Innovation Committee [RCBS20210706092343014]
- National Natural Science Foundation of China (NSFC) [52027817]
- National Natural Science Foundation of China [03012800001]
- Guangdong Major Project of Basic and Applied Basic Research [2019B030302007]
- Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials [2019B121205002]
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An efficient energy cascade channel is developed by introducing sodium bromide in mixed-halide perovskites, resulting in improved performance of blue perovskite light-emitting diodes.
Solution processable quasi-2D (Q-2D) perovskite materials are emerging as a promising candidate for blue light source in full-color display applications due to their good color saturation property, high brightness, and spectral tunability. Herein, an efficient energy cascade channel is developed by introducing sodium bromide (NaBr) in phenyl-butylammonium (PBA)-containing mixed-halide Q-2D perovskites for a blue perovskite light-emitting diode (PeLED). The incorporation of alkali metal contributes to the nucleation and growth of Q-2D perovskites into graded distribution of domains with different layer number . The study of excitation dynamics by transient absorption (TA) spectroscopy confirms that NaBr induces more Q-2D perovskite phases with small n number, providing a graded energy cascade pathway to facilitate more efficient energy transfer processes. In addition, the nonradiative recombination within the Q-2D perovskites is significantly suppressed upon Na+ incorporation, as validated by the trap density estimation. Consequently, the optimized blue PeLEDs manifest a peak external quantum efficiency (EQE) of 7.0% emitting at 486 nm with a maximum luminance of 1699 cd m(-2). It is anticipated that these findings will improve the understanding of alkali-metal-assisted optimization of Q-2D perovskites and pave the way toward high-performance blue PeLEDs.
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