Han Boning, Yuan Shichen, Fang Tao, Zhang Fengjuan, Shi Zhifeng, Song Jizhong
School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
MIIT Key Laboratory of Advanced Display Materials and Devices, Institute of Optoelectronics & Nanomaterials, Nanjing 210094, China.
ACS Appl Mater Interfaces. 2020 Mar 25;12(12):14224-14232. doi: 10.1021/acsami.0c02768. Epub 2020 Mar 16.
Metal halide perovskites have been focused as a candidate applied as a promising luminescent material for next-generation high-quality lighting and high-definition display. However, as perovskite films formed, high density of defects would be produced in solution processing inevitably, leading to low exciton recombination efficiency in light-emitting diodes (LEDs). Herein, a facile and novel self-passivation strategy to inhibit defect formation in perovskite films for constructing high-performance LEDs is developed. For the first time, we introduce 1,4,8,11-tetraazacyclotetradecane (cyclam) in perovskite precursor solution, and it spontaneously passivates defect states of CsPbBr-based perovskites by coaction between amine and uncoordinated lead ions during spin-coating without an anti-solvent process. Furthermore, as a delocalized system, cyclam also possesses chemical properties that facilitate exciton transportation. The proposed passivation strategy boosts the external quantum efficiency from 1.25% (control device) to 16.24% (cyclam-passivated device). Furthermore, defect passivation is also conductive to reduce LED degradation paths and improve device stability as the extrapolated lifetime () of LEDs at an initial brightness of 100 cd/m is increased from 0.9 to 127 h. These findings indicate that the introduction of cyclam is highly effective to enhance the performance of LEDs, and such a strategy in effectively reducing the defects could be also applied in other perovskite-based devices, such as lasers, solar cells, and photodetectors.
金属卤化物钙钛矿作为一种有潜力的发光材料，有望应用于下一代高质量照明和高清显示，因此受到了广泛关注。然而，在溶液处理过程中形成钙钛矿薄膜时，不可避免地会产生高密度缺陷，导致发光二极管（LED）中的激子复合效率较低。在此，我们开发了一种简便新颖的自钝化策略，用于抑制钙钛矿薄膜中的缺陷形成，以构建高性能LED。我们首次在钙钛矿前驱体溶液中引入1,4,8,11-四氮杂环十四烷（环胺），在旋涂过程中，它通过胺与未配位铅离子之间的协同作用自发钝化CsPbBr基钙钛矿的缺陷态，无需抗溶剂处理。此外，作为一种离域体系，环胺还具有促进激子传输的化学性质。所提出的钝化策略将外部量子效率从1.25%（对照器件）提高到16.24%（环胺钝化器件）。此外，缺陷钝化还有助于减少LED的退化路径并提高器件稳定性，因为在初始亮度为100 cd/m²时，LED的外推寿命（）从0.9小时增加到127小时。这些发现表明，引入环胺对提高LED性能非常有效，这种有效减少缺陷的策略也可应用于其他基于钙钛矿的器件，如激光器、太阳能电池和光电探测器。
