Transcending the slow bimolecular recombination in lead-halide perovskites for electroluminescence

• Main Authors: Huang, Wei, Xing, Guichuan, Wu, Bo, Wu, Xiangyang, Li, Mingjie, Du, Bin, Wei, Qi, Guo, Jia, Yeow, Edwin K. L., Sum, Tze Chien
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2017
• Subjects: Materials for Devices; Optical Physics
• Online Access: https://hdl.handle.net/10356/83913; http://hdl.handle.net/10220/42862
• Institution: Nanyang Technological University

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.