Journal
ADVANCED MATERIALS
Volume 34, Issue 30, Pages -Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adma.202202042
Keywords
film formation; high luminance; perovskite light-emitting diodes; stability
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Funding
- NSFC/RGC Joint Research Scheme (RGC) from the Research Grants Council of Hong Kong [N_CUHK449/19]
- General Research Fund (RGC) from the Research Grants Council of Hong Kong [14307819, 14207221]
- Collaborative Research Fund (RGC) from the Research Grants Council of Hong Kong [C7035-20G]
- NWO (Netherlands Organization for Scientific Research) START-UP from The Netherlands
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By using diammonium halides to regulate the formation of mixed bromide-iodide perovskite films, the performance of 3D mixed-halide perovskite-based light-emitting diodes (LEDs) can be improved, resulting in devices with record luminance and half-lifetime.
3D mixed-halide perovskite-based red emitters combine excellent charge-transport characteristics with simple solution processing and good film formation; however, light-emitting diodes (LEDs) based on these emitters cannot yet outperform their nanocrystal counterparts. Here the use of diammonium halides in regulating the formation of mixed bromide-iodide perovskite films is explored. It is found that the diammonium cations preferentially bond to Pb-Br, rather than Pb-I, octahedra, promoting the formation of quasi-2D phases. It is proposed that the perovskite formation is initially dominated by the crystallization of the thermodynamically more favorable 3D phase, but, as the solution gets depleted from the regular A cations, thin shells of amorphous quasi-2D perovskites form. This leads to crystalline perovskite grains with efficiently passivated surfaces and reduced lattice strain. As a result, the diammonium-treated perovskite LEDs demonstrate a record luminance (10745 cd m(-2)) and half-lifetime among 3D perovskite-based red LEDs.
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