Journal
ADVANCED MATERIALS
Volume 33, Issue 40, Pages -Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adma.202102246
Keywords
alkali-metal cations; crystallization kinetics; perovskite light-emitting diodes; quasi-2D perovskites
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Funding
- National Key Research and Development Program of China [2017YFA0206701, 2020YFB1506400]
- National Natural Science Foundation of China [51972004]
- Tencent Foundation through the XPLORER PRIZE
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By manipulating the crystallization kinetics of different-n phases, a more efficient energy transfer in Q-2D perovskites is achieved, leading to highly efficient green LEDs.
Quasi-2D (Q-2D) perovskites are promising materials applied in light-emitting diodes (LEDs) due to their high exciton binding energy and quantum confinement effects. However, Q-2D perovskites feature a multiphase structure with abundant grain boundaries and interfaces, leading to nonradiative loss during the energy-transfer process. Here, a more efficient energy transfer in Q-2D perovskites is achieved by manipulating the crystallization kinetics of different-n phases. A series of alkali-metal bromides is utilized to manipulate the nucleation and growth of Q-2D perovskites, which is likely associated with the Coulomb interaction between alkali-metal ions and the negatively charged PbBr64- frames. The incorporation of K+ is found to restrict the nucleation of high-n phases and allows the subsequent growth of low-n phases, contributing to a spatially more homogeneous distribution of different-n phases and promoted energy transfer. As a result, highly efficient green Q-2D perovskites LEDs with a champion EQE of 18.15% and a maximum brightness of 25 800 cd m(-2) are achieved. The findings affirm a novel method to optimize the performance of Q-2D perovskite LEDs.
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