Transcending the slow bimolecular recombination in lead-halide perovskites for electroluminescence.
Transcending the slow bimolecular recombination in lead-halide perovskites for electroluminescence.
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超越卤化铅钙钛矿中缓慢的双分子重组，实现电致发光
DOI：
10.1038/ncomms14558
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发表时间：
2017-02-27
影响因子：
16.6
通讯作者：
Huang W
中科院分区：
文献类型：
--
作者：
Xing G;Wu B;Wu X;Li M;Du B;Wei Q;Guo J;Yeow EK;Sum TC;Huang W
缓慢的双分子重组驱动了三维卤化铅钙钛矿出色的光伏性能，相反，这是电致发光的基本限制。在典型电荷密度低于1015 cm−3的电致发光工作条件下，三维钙钛矿中的缺陷态捕获与双分子辐射重组有效竞争。在这里，我们利用范德-瓦尔斯耦合Ruddlesden-Popper钙钛矿多量子阱克服了这一限制。注入的载流子通过量子耦合从相邻的薄层（n≤4）多量子阱快速定位到厚层（n≥5）多量子阱，效率极高（超过85%）。光发射源于厚多量子阱中的激子复合，其衰变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钙钛矿提供了在单相成分中不可用的新功能，允许超越卤化铅钙钛矿中缓慢的双分子重组瓶颈，以实现高效电致发光。三维卤化物钙钛矿中缓慢的双分子重组是电致发光效率的一个基本限制。利用时间分辨光谱，Xing等人证明了这一限制可以通过采用范德-瓦尔斯耦合的多量子阱结构来克服。
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. Slow bimolecular recombination in three-dimensional halide perovskites represents a fundamental limitation for electroluminescence efficiency. Using time-resolved spectroscopy Xing et al. demonstrate that this limitation can be overcome by employing van-der-Waals-coupled multiple quantum well structures.