The slow bimolecular recombination that drives three-dimensional lead-halide perovskites' outstanding photovoltaic performance is conversely a fundamental limitation for electroluminescence. Under electroluminescence working conditions with typical charge densities lower than 1015 cm−3, defect-states trapping in three-dimensional perovskites competes effectively with the bimolecular radiative recombination. Herein, we overcome this limitation using van-der-Waals-coupled Ruddlesden-Popper perovskite multi-quantum-wells. Injected charge carriers are rapidly localized from adjacent thin few layer (n≤4) multi-quantum-wells to the thick (n≥5) multi-quantum-wells with extremely high efficiency (over 85%) through quantum coupling. Light emission originates from excitonic recombination in the thick multi-quantum-wells at much higher decay rate and efficiency than bimolecular recombination in three-dimensional perovskites. These multi-quantum-wells retain the simple solution processability and high charge carrier mobility of two-dimensional lead-halide perovskites. Importantly, these Ruddlesden-Popper perovskites offer new functionalities unavailable in single phase constituents, permitting the transcendence of the slow bimolecular recombination bottleneck in lead-halide perovskites for efficient electroluminescence.
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机译:相反,驱动三维卤化铅钙钛矿杰出光伏性能的缓慢双分子复合反过来是电致发光的基本限制。在典型的电荷密度低于10 15 sup> cm -3 sup>的电致发光工作条件下,捕获在三维钙钛矿中的缺陷态与双分子辐射复合有效竞争。在本文中,我们使用范德华耦合的Ruddlesden-Popper钙钛矿多量子阱克服了这一限制。通过量子耦合,注入的载流子以极高的效率(超过85%)从相邻的几层(n≤4)多量子阱迅速地定位到厚(n≥5)的多量子阱。发光源于厚的多量子阱中的激子复合,其衰减速率和效率远高于三维钙钛矿中的双分子复合。这些多量子阱保留了二维卤化铅钙钛矿的简单溶液可加工性和高载流子迁移率。重要的是,这些Ruddlesden-Popper钙钛矿提供了单相成分所不具备的新功能,从而允许慢速双分子复合瓶颈超越卤化铅钙钛矿中的有效电致发光。
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