Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 14, Issue 41, Pages 46857-46865Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.2c12375
Keywords
mixed-halide perovskites; near-unity PLQY; blue-emissive perovskites; pure-blue LEDs; Cl vacancy filling
Funding
- National Natural Science Foundation of China [22179072, 22088102]
- Natural Science Foundation of Shandong Province [ZR2021QF006]
- Outstanding Youth Science Foundation of Shandong Province (Overseas) [2022HWYQ-006]
- Qilu Youth Scholar Foundation of Shandong University [62460082163114]
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This study successfully synthesized efficient blue emitters by optimizing the synthesis process and proposed new materials design strategies.
Mixed-halide (Cl and Br) perovskite nanocrystals (NCs) are of particular interest because they hold great potential for use in high-efficiency blue light-emitting diodes (LEDs). Generally, mixed-halide compounds are obtained by either a one-step synthesis with simultaneous addition of both halide precursors or a postsynthetic anion exchange using the opposite halogen. However, both strategies fail to prevent the formation of deep-level Cl vacancy defects, rendering the photoluminescence quantum yields (PLQYs) typically lower than 30%. Here, by optimizing both thermodynamic and kinetic processes, we devise a two-step hot-injection approach, which simultaneously realizes Cl vacancy filling and efficient anion exchange between Cl- and Br-. Both the identity of Br precursors and their injection temperature are revealed to be critical in transforming those highly defective CsPbCl3 NCs to defect-free CsPb(Cl/Br)(3). The optimally synthesized NCs exhibit a saturated blue emission at similar to 460 nm with a near-unity PLQY and a narrow emission bandwidth of 18 nm, which represents one of the most efficient blue emitters reported so far. The turn-on voltage of the ensuing LEDs is similar to 4.0 V, which is lower than those of most other mixed-halide perovskites. In addition, LEDs exhibit a stable electroluminescence peak at 460 nm under a high bias voltage of 8.0 V. We anticipate that our findings will provide new insights into the materials design strategies for producing high-optoelectronic-quality Cl-containing perovskites.
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