Institute of Applied Physics and Materials Engineering, University of Macau, Macao SAR 999078, China.
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
Nat Commun. 2017 Feb 27;8:14558. doi: 10.1038/ncomms14558.
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 10 cm, 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.
驱动三维卤铅钙钛矿优异光伏性能的缓慢双分子复合过程，反过来却成为电致发光的一个基本限制。在典型电荷密度低于 10 cm 的电致发光工作条件下，三维钙钛矿中的缺陷态俘获有效地与双分子辐射复合竞争。在此，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。注入的载流子通过量子耦合，从相邻的薄少层（n≤4）多量子阱中快速局域到厚多量子阱（n≥5），效率极高（超过 85%）。发光源于厚多量子阱中的激子复合，其衰减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铅钙钛矿的简单溶液处理和高载流子迁移率。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，从而克服了卤铅钙钛矿中缓慢双分子复合瓶颈，实现了高效电致发光。
