Li Zhiqi, Ren Zhiwei, Liang Qiong, Fong Patrick W K, Tian Jianjun, Li Gang
Department of Electrical and Electronic Engineering, Photonic Research Institute (PRI), Research Institute of Smart Energy (RISE), The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, 2766 5111, China.
Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.
Adv Mater. 2024 Jul;36(27):e2313981. doi: 10.1002/adma.202313981. Epub 2024 Apr 29.
Excess ammonium halides as composition additives are widely employed in perovskite light-emitting diodes (PeLEDs), aiming to achieve high performance by controlling crystallinity and passivating defects. However, an in-depth understanding of whether excess organoammonium components affect the film physical/electrical properties and the resultant device instability is still lacking. Here, the trade-off between the performance and stability in high-efficiency formamidinium lead iodide (FAPbI)-based PeLEDs with excess ammonium halides is pointed, and the underlying mechanism is explored. Systematic experimental and theoretical studies reveal that excess halide salt-induced ion-doping largely alters the PeLEDs properties (e.g., carrier injection, field-dependent ion-drifting, defect physics, and phase stability). A surface clean assisted cross-linking strategy is demonstrated to eliminate the adverse impact of composition modulation and boost the operational stability without sacrificing the efficiency, achieving a high efficiency of 23.6%, a high radiance of 964 W sr m (The highest value for FAPbI based PeLEDs), and a prolong lifetime of 106.1 h at large direct current density (100 mA cm), concurrently. The findings uncovered an important link between excess halide salts and the device performance, providing a guideline for rational design of stable, bright, and high efficiency PeLEDs.
过量卤化铵作为成分添加剂被广泛应用于钙钛矿发光二极管（PeLEDs）中，旨在通过控制结晶度和钝化缺陷来实现高性能。然而，目前仍缺乏对过量有机铵成分是否会影响薄膜物理/电学性质以及由此导致的器件不稳定性的深入理解。在此，指出了在含有过量卤化铵的高效碘化甲脒铅（FAPbI）基PeLEDs中性能与稳定性之间的权衡，并探索了其潜在机制。系统的实验和理论研究表明，过量卤化物盐诱导的离子掺杂在很大程度上改变了PeLEDs的性质（例如，载流子注入、场致离子漂移、缺陷物理和相稳定性）。实验证明了一种表面清洁辅助交联策略，该策略可以消除成分调制的不利影响，并在不牺牲效率的情况下提高器件的运行稳定性，同时实现了23.6%的高效率、964 W sr⁻¹ m⁻²的高辐射亮度（这是基于FAPbI的PeLEDs的最高值）以及在大直流电流密度（100 mA cm⁻²）下106.1小时的延长寿命。这些发现揭示了过量卤化物盐与器件性能之间的重要联系，为合理设计稳定、明亮且高效的PeLEDs提供了指导。
