Lee Seungjin, Jang Chung Hyeon, Nguyen Thanh Luan, Kim Su Hwan, Lee Kyung Min, Chang Kiseok, Choi Su Seok, Kwak Sang Kyu, Woo Han Young, Song Myoung Hoon
School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan, 44919, Republic of Korea.
Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada.
Adv Mater. 2019 Jun;31(24):e1900067. doi: 10.1002/adma.201900067. Epub 2019 Apr 26.
Metal halide perovskites (MHPs) have attracted significant attention as light-emitting materials owing to their high color purities and tunabilities. A key issue in perovskite light-emitting diodes (PeLEDs) is the fabrication of an optimal charge transport layer (CTL), which has desirable energy levels for efficient charge injection while blocking opposite charges and enabling perovskite layer growth with reduced interfacial defects. Herein, two poly(fluorene-phenylene)-based anionic conjugated polyelectrolytes (CPEs) with different counterions (K and tetramethylammonium (TMA )) are presented as multifunctional passivating and hole-transporting layers (HTLs). The crystal growth of MHPs grown on different HTLs is investigated through X-ray photoelectron spectroscopy, X-ray diffraction, and density functional theory calculation. The CPE bearing the TMA counterions remarkably improves the growth of perovskites with suppressed interfacial defects, leading to significantly enhanced emission properties and device performance. The luminescent properties are further enhanced via aging and electrical stress application with effective rearrangement of the counterions on the interfacial defects in the perovskites. Finally, efficient formamidinium lead tribromide-based quasi-2D PeLEDs with an external quantum efficiency of 10.2% are fabricated. Using CPEs with varying counterions as a CTL can serve as an effective method for controlling the interfacial defects and improving perovskite-based optoelectronic device properties.
金属卤化物钙钛矿（MHPs）因其高色纯度和可调性作为发光材料受到了广泛关注。钙钛矿发光二极管（PeLEDs）中的一个关键问题是制备最佳的电荷传输层（CTL），该层具有理想的能级，以实现高效的电荷注入，同时阻挡相反电荷，并使钙钛矿层在减少界面缺陷的情况下生长。在此，提出了两种具有不同抗衡离子（K和四甲基铵（TMA））的基于聚（芴-亚苯基）的阴离子共轭聚合物电解质（CPEs）作为多功能钝化和空穴传输层（HTLs）。通过X射线光电子能谱、X射线衍射和密度泛函理论计算研究了在不同HTLs上生长的MHPs的晶体生长情况。带有TMA抗衡离子的CPE显著改善了钙钛矿的生长，抑制了界面缺陷，从而显著提高了发光性能和器件性能。通过老化和施加电应力，抗衡离子在钙钛矿界面缺陷上有效重排，进一步增强了发光性能。最后，制备出了基于甲脒三溴化铅的高效准二维PeLEDs，其外量子效率为10.2%。使用具有不同抗衡离子的CPE作为CTL可以作为一种控制界面缺陷和改善基于钙钛矿的光电器件性能的有效方法。
